Table of Contents

Solution Summary
Difficulty
Categories

Solution Summary

ID	Problem	Leetcode ID	Categories	Difficulty
1		429
2		116
3		297
4		430
5		284
6	Get Maximum in Generated Array	1646	Array, Dynamic Programming, Simulation	Easy
7	Minimum Deletions to Make Character Frequencies Unique	1647	String, Greedy, Sorting	Medium
8	Sell Diminishing-Valued Colored Balls	1648	Array, Math, Binary Search, Greedy, Sorting, Heap (Priority Queue)	Medium
9	Design an Ordered Stream	1656	Array, Hash Table, Design, Data Stream	Easy
10	Determine if Two Strings Are Close	1657	Hash Table, String, Sorting	Medium
11	Check If Two String Arrays are Equivalent	1662	Array, String	Easy
12	Smallest String With A Given Numeric Value	1663	String, Greedy	Medium
13	Richest Customer Wealth	1672	Array, Matrix	Easy
14	Find the Most Competitive Subsequence	1673	Array, Stack, Greedy, Monotonic Stack	Medium
15	Minimum Moves to Make Array Complementary	1674	Array, Hash Table, Prefix Sum	Medium
16	Count of Matches in Tournament	1688	Math, Simulation	Easy
17	Partitioning Into Minimum Number Of Deci-Binary Numbers	1689	String, Greedy	Medium
18	Determine if String Halves Are Alike	1704	String, Counting	Easy
19	Maximum Number of Eaten Apples	1705	Array, Greedy, Heap (Priority Queue)	Medium
20	Where Will the Ball Fall	1706	Array, Dynamic Programming, Depth-First Search, Matrix, Simulation	Medium
21	Maximum Units on a Truck	1710	Array, Greedy, Sorting	Easy
22	Count Good Meals	1711	Array, Hash Table	Medium
23	Decode XORed Array	1720	Array, Bit Manipulation	Easy
24	Swapping Nodes in a Linked List	1721	Linked List, Two Pointers	Medium
25	Minimize Hamming Distance After Swap Operations	1722	Array, Depth-First Search, Union Find	Medium
26	Find Minimum Time to Finish All Jobs	1723	Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask	Hard
27	Number Of Rectangles That Can Form The Largest Square	1725	Array	Easy
28	Tuple with Same Product	1726	Array, Hash Table	Medium
29	Largest Submatrix With Rearrangements	1727	Array, Greedy, Sorting, Matrix	Medium
30	Latest Time by Replacing Hidden Digits	1736	String, Greedy	Easy
31	Change Minimum Characters to Satisfy One of Three Conditions	1737	Hash Table, String, Counting, Prefix Sum	Medium
32	Find Kth Largest XOR Coordinate Value	1738	Array, Divide and Conquer, Bit Manipulation, Heap (Priority Queue), Matrix, Prefix Sum, Quickselect	Medium
33	Building Boxes	1739	Math, Binary Search, Greedy	Hard
34	Maximum Number of Balls in a Box	1742	Hash Table, Math, Counting	Easy
35	Restore the Array From Adjacent Pairs	1743	Array, Hash Table	Medium
36	Check if Array Is Sorted and Rotated	1752	Array	Easy
37	Minimum Changes To Make Alternating Binary String	1758	String	Easy
38	Count Number of Homogenous Substrings	1759	Math, String	Medium
39	Minimum Degree of a Connected Trio in a Graph	1761	Graph	Hard
40	Merge Strings Alternately	1768	Two Pointers, String	Easy
41	Minimum Number of Operations to Move All Balls to Each Box	1769	Array, String	Medium
42	Maximum Score from Performing Multiplication Operations	1770	Array, Dynamic Programming	Medium
43	Maximize Palindrome Length From Subsequences	1771	String, Dynamic Programming	Hard
44	Check if Binary String Has at Most One Segment of Ones	1784	String	Easy
45	Check if One String Swap Can Make Strings Equal	1790	Hash Table, String, Counting	Easy
46	Find Center of Star Graph	1791	Graph	Easy
47	Maximum Average Pass Ratio	1792	Array, Greedy, Heap (Priority Queue)	Medium
48	Maximum Ascending Subarray Sum	1800	Array	Easy
49	Number of Orders in the Backlog	1801	Array, Heap (Priority Queue), Simulation	Medium
50	Number of Different Integers in a String	1805	Hash Table, String	Easy
51	Truncate Sentence	1816	Array, String	Easy
52	Finding the Users Active Minutes	1817	Array, Hash Table	Medium
53	Minimum Absolute Sum Difference	1818	Array, Binary Search, Sorting, Ordered Set	Medium
54	Number of Different Subsequences GCDs	1819	Array, Math, Counting, Number Theory	Hard
55	Sign of the Product of an Array	1822	Array, Math	Easy
56	Find the Winner of the Circular Game	1823	Array, Math, Recursion, Queue, Simulation	Medium
57	Minimum Sideway Jumps	1824	Array, Dynamic Programming, Greedy	Medium
58	Finding MK Average	1825	Design, Queue, Heap (Priority Queue), Ordered Set	Hard
59	Maximum Ice Cream Bars	1833	Array, Greedy, Sorting	Medium
60	Single-Threaded CPU	1834	Array, Sorting, Heap (Priority Queue)	Medium
61	Find XOR Sum of All Pairs Bitwise AND	1835	Array, Math, Bit Manipulation	Hard
62	Check if the Sentence Is Pangram	1832	Hash Table, String	Easy
63	Frequency of the Most Frequent Element	1838	Array, Binary Search, Greedy, Sliding Window, Sorting, Prefix Sum	Medium
64	Sum of Digits in Base K	1837	Math	Easy
65	Longest Substring Of All Vowels in Order	1839	String, Sliding Window	Medium
66	Maximum Building Height	1840	Array, Math	Hard
67	Minimum Interval to Include Each Query	1851	Array, Binary Search, Line Sweep, Sorting, Heap (Priority Queue)	Hard
68	Minimum Number of Swaps to Make the Binary String Alternating	1864	String, Greedy	Medium
69	Finding Pairs With a Certain Sum	1865	Array, Hash Table, Design	Medium
70	Minimum Distance to the Target Element	1848	Array	Easy
71	Splitting a String Into Descending Consecutive Values	1849	String, Backtracking	Medium
72	Next Permutation	31	Array, Two Pointers	Medium
73	Minimum Adjacent Swaps to Reach the Kth Smallest Number	1850	Two Pointers, String, Greedy	Medium
74	Maximum Distance Between a Pair of Values	1855	Array, Two Pointers, Binary Search, Greedy	Medium
75	Maximum Subarray Min-Product	1856	Array, Stack, Monotonic Stack, Prefix Sum	Medium
76	Longer Contiguous Segments of Ones than Zeros	1869	String	Easy
77	Minimum Speed to Arrive on Time	1870	Array, Binary Search	Medium
78	Jump Game VII	1871	Two Pointers, String, Prefix Sum	Medium
79	Largest Color Value in a Directed Graph	1857	Hash Table, Dynamic Programming, Graph, Topological Sort, Memoization, Counting	Hard
80	Maximum Population Year	1854	Array, Counting	Easy
81	Process Tasks Using Servers	1882	Array, Heap (Priority Queue)	Medium
82	Sum of All Subset XOR Totals	1863	Array, Backtracking, Bit Manipulation	Easy
83	Number of Ways to Rearrange Sticks With K Sticks Visible	1866	Math, Dynamic Programming, Combinatorics	Hard
84	Determine Whether Matrix Can Be Obtained By Rotation	1886	Array, Matrix	Easy
85	Stone Game VIII	1872	Array, Math, Dynamic Programming, Prefix Sum, Game Theory	Hard
86	Redistribute Characters to Make All Strings Equal	1897	Hash Table, String, Counting	Easy
87	Merge Triplets to Form Target Triplet	1899	Array, Greedy	Medium
88	Check if Word Equals Summation of Two Words	1880	String	Easy
89	Maximum Value after Insertion	1881	String, Greedy	Medium
90	Minimum Skips to Arrive at Meeting On Time	1883	Array, Dynamic Programming	Hard
91	Largest Odd Number in String	1903	Math, String, Greedy	Easy
92	Count Sub Islands	1905	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix	Medium
93	Minimum Absolute Difference Queries	1906	Array, Hash Table	Medium
94	Reduction Operations to Make the Array Elements Equal	1887	Array, Sorting	Medium
95	Minimum Space Wasted From Packaging	1889	Array, Binary Search, Sorting, Prefix Sum	Hard
96	Minimum Number of Flips to Make the Binary String Alternating	1888	String, Greedy	Medium
97	Maximum Product Difference Between Two Pairs	1913	Array, Sorting	Easy
98	Cyclically Rotating a Grid	1914	Array, Matrix, Simulation	Medium
99	Number of Wonderful Substrings	1915	Hash Table, String, Bit Manipulation, Prefix Sum	Medium
100	Count Ways to Build Rooms in an Ant Colony	1916	Math, Dynamic Programming, Tree, Graph, Topological Sort, Combinatorics	Hard
101	Maximum Number of Removable Characters	1898	Array, String, Binary Search	Medium
102	Find K Closest Elements	658	Array, Two Pointers, Binary Search, Sorting, Heap (Priority Queue)	Medium
103	Max Sum of Rectangle No Larger Than K	363	Array, Binary Search, Dynamic Programming, Matrix, Ordered Set	Hard
104	Build Array from Permutation	1920	Array, Simulation	Easy
105	Eliminate Maximum Number of Monsters	1921	Array, Greedy, Sorting	Medium
106	Count Good Numbers	1922	Math, Recursion	Medium
107	Count Vowels Permutation	1220	Dynamic Programming	Hard
108	Gray Code	89	Math, Backtracking, Bit Manipulation	Medium
109	Reshape the Matrix	566	Array, Matrix, Simulation	Easy
110	Remove One Element to Make the Array Strictly Increasing	1909	Array	Easy
111	Remove All Occurrences of a Substring	1910	String	Medium
112	Maximum Alternating Subsequence Sum	1911	Array, Dynamic Programming	Medium
113	Reduce Array Size to The Half	1338	Array, Hash Table, Greedy, Sorting, Heap (Priority Queue)	Medium
114	The Number of Full Rounds You Have Played	1904	Math, String	Medium
115	Kth Smallest Element in a Sorted Matrix	378	Array, Binary Search, Sorting, Heap (Priority Queue), Matrix	Medium
116	Maximum Length of Repeated Subarray	718	Array, Binary Search, Dynamic Programming, Sliding Window, Rolling Hash, Hash Function	Medium
117	Longest Increasing Subsequence	300	Array, Binary Search, Dynamic Programming	Medium
118	Concatenation of Array	1929	Array	Easy
119	Painting a Grid With Three Different Colors	1931	Dynamic Programming	Hard
120	Merge BSTs to Create Single BST	1932	Hash Table, Binary Search, Tree, Depth-First Search, Binary Tree	Hard
121	Unique Length-3 Palindromic Subsequences	1930	Hash Table, String, Prefix Sum	Medium
122	Isomorphic Strings	205	Hash Table, String	Easy
123	Custom Sort String	791	Hash Table, String, Sorting	Medium
124	Find Peak Element	162	Array, Binary Search	Medium
125	Valid Triangle Number	611	Array, Two Pointers, Binary Search, Greedy, Sorting	Medium
126	Count Square Sum Triples	1925	Math, Enumeration	Easy
127	Sum Game	1927	Math, Greedy, Game Theory	Medium
128	Nearest Exit from Entrance in Maze	1926	Array, Breadth-First Search, Matrix	Medium
129	Three Equal Parts	927	Array, Math	Hard
130	Maximum Number of Words You Can Type	1935	Hash Table, String	Easy
131	Add Minimum Number of Rungs	1936	Array, Greedy	Medium
132	Maximum Number of Points with Cost	1937	Array, Dynamic Programming	Medium
133	Push Dominoes	838	Two Pointers, String, Dynamic Programming	Medium
134	Partition Array into Disjoint Intervals	915	Array	Medium
135	Binary Tree Pruning	814	Tree, Depth-First Search, Binary Tree	Medium
136	Sum of Digits of String After Convert	1945	String, Simulation	Easy
137	Maximum Compatibility Score Sum	1947	Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask	Medium
138	Non-negative Integers without Consecutive Ones	600	Dynamic Programming	Hard
139	3Sum Closest	16	Array, Two Pointers, Sorting	Medium
140	Beautiful Array	932	Array, Math, Divide and Conquer	Medium
141	01 Matrix	542	Array, Dynamic Programming, Breadth-First Search, Matrix	Medium
142	Map Sum Pairs	677	Hash Table, String, Design, Trie	Medium
143	Check if All Characters Have Equal Number of Occurrences	1941	Hash Table, String, Counting	Easy
144	The Number of the Smallest Unoccupied Chair	1942	Array, Heap (Priority Queue), Ordered Set	Medium
145	Describe the Painting	1943	Array, Prefix Sum	Medium
146	Number of Visible People in a Queue	1944	Array, Stack, Monotonic Stack	Hard
147	Trapping Rain Water	42	Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack	Hard
148	Three Divisors	1952	Math	Easy
149	Minimum Garden Perimeter to Collect Enough Apples	1954	Math, Binary Search	Medium
150	Count Number of Special Subsequences	1955	Array, Dynamic Programming	Hard
151	Maximum Number of Weeks for Which You Can Work	1953	Array, Greedy	Medium
152	Making A Large Island	827	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix	Hard
153	Subsets II	90	Array, Backtracking, Bit Manipulation	Medium
154	Path Sum II	113	Backtracking, Tree, Depth-First Search, Binary Tree	Medium
155	Combinations	77	Array, Backtracking	Medium
156	Permutations	46	Array, Backtracking	Medium
157	Permutations II	47	Array, Backtracking	Medium
158	Stone Game	877	Array, Math, Dynamic Programming, Game Theory	Medium
159	Subsets	78	Array, Backtracking, Bit Manipulation	Medium
160	Palindrome Partitioning II	132	String, Dynamic Programming	Hard
161	Combination Sum	39	Array, Backtracking	Medium
162	Combination Sum II	40	Array, Backtracking	Medium
163	Remove Stones to Minimize the Total	1962	Array, Heap (Priority Queue)	Medium
164	Minimum Number of Swaps to Make the String Balanced	1963	Two Pointers, String, Stack, Greedy	Medium
165	Find the Longest Valid Obstacle Course at Each Position	1964	Array, Binary Search, Binary Indexed Tree	Hard
166	Check If String Is a Prefix of Array	1961	Array, String	Easy
167	Add Strings	415	Math, String, Simulation	Easy
168	Largest Number After Mutating Substring	1946	Array, String, Greedy	Medium
169	Flip String to Monotone Increasing	926	String, Dynamic Programming	Medium
170	Array of Doubled Pairs	954	Array, Hash Table, Greedy, Sorting	Medium
171	Group Anagrams	49	Hash Table, String, Sorting	Medium
172	Set Matrix Zeroes	73	Array, Hash Table, Matrix	Medium
173	Word Ladder II	126	Hash Table, String, Backtracking, Breadth-First Search	Hard
174	Remove Boxes	546	Array, Dynamic Programming, Memoization	Hard
175	Array With Elements Not Equal to Average of Neighbors	1968	Array, Greedy, Sorting	Medium
176	Minimum Non-Zero Product of the Array Elements	1969	Math, Greedy, Recursion	Medium
177	Last Day Where You Can Still Cross	1970	Array, Binary Search, Depth-First Search, Breadth-First Search, Union Find, Matrix	Hard
178	Range Sum Query - Immutable	303	Array, Design, Prefix Sum	Easy
179	Minimum Window Substring	76	Hash Table, String, Sliding Window	Hard
180	Count Good Nodes in Binary Tree	1448	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Medium
181	Check if Move is Legal	1958	Array, Matrix, Enumeration	Medium
182	Minimum Total Space Wasted With K Resizing Operations	1959	Array, Dynamic Programming	Medium
183	Delete Characters to Make Fancy String	1957	String	Easy
184	Decode Ways	91	String, Dynamic Programming	Medium
185	Remove Duplicates from Sorted Array	26	Array, Two Pointers	Easy
186	Best Time to Buy and Sell Stock II	122	Array, Dynamic Programming, Greedy	Medium
187	Rotate Array	189	Array, Math, Two Pointers	Medium
188	Contains Duplicate	217	Array, Hash Table, Sorting	Easy
189	Single Number	136	Array, Bit Manipulation	Easy
190	Maximum Product of Splitted Binary Tree	1339	Tree, Depth-First Search, Binary Tree	Medium
191	Intersection of Two Arrays II	350	Array, Hash Table, Two Pointers, Binary Search, Sorting	Easy
192	Intersection of Two Arrays	349	Array, Hash Table, Two Pointers, Binary Search, Sorting	Easy
193	Plus One	66	Array, Math	Easy
194	Move Zeroes	283	Array, Two Pointers	Easy
195	Two Sum	1	Array, Hash Table	Easy
196	Rotate Image	48	Array, Math, Matrix	Medium
197	Valid Sudoku	36	Array, Hash Table, Matrix	Medium
198	Reverse String	344	Two Pointers, String, Recursion	Easy
199	Reverse Integer	7	Math	Easy
200	First Unique Character in a String	387	Hash Table, String, Queue, Counting	Easy
201	Valid Anagram	242	Hash Table, String, Sorting	Easy
202	Valid Palindrome	125	Two Pointers, String	Easy
203	String to Integer (atoi)	8	String	Medium
204	Implement strStr()	28	Two Pointers, String, String Matching	Easy
205	Minimum Time to Type Word Using Special Typewriter	1974	String, Greedy	Easy
206	Maximum Matrix Sum	1975	Array, Greedy, Matrix	Medium
207	Find Greatest Common Divisor of Array	1979	Array, Math	Easy
208	Find Unique Binary String	1980	Array, String, Backtracking	Medium
209	Minimize the Difference Between Target and Chosen Elements	1981	Array, Dynamic Programming, Matrix	Medium
210	Sudoku Solver	37	Array, Backtracking, Matrix	Hard
211	Merge Intervals	56	Array, Sorting	Medium
212	Rectangle Area II	850	Array, Segment Tree, Line Sweep, Ordered Set	Hard
213	Two Sum IV - Input is a BST	653	Hash Table, Two Pointers, Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree	Easy
214	Complex Number Multiplication	537	Math, String, Simulation	Medium
215	Count and Say	38	String	Medium
216	Longest Common Prefix	14	String	Easy
217	Sum of Square Numbers	633	Math, Two Pointers, Binary Search	Medium
218	Delete Node in a Linked List	237	Linked List	Easy
219	Remove Nth Node From End of List	19	Linked List, Two Pointers	Medium
220	Verify Preorder Serialization of a Binary Tree	331	String, Stack, Tree, Binary Tree	Medium
221	Longest Uncommon Subsequence II	522	Array, Hash Table, Two Pointers, String, Sorting	Medium
222	Minimum Difference Between Highest and Lowest of K Scores	1984	Array, Sorting	Easy
223	Find the Kth Largest Integer in the Array	1985	Array, String, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect	Medium
224	Maximum Profit in Job Scheduling	1235	Array, Binary Search, Dynamic Programming, Sorting	Hard
225	Minimum Number of Work Sessions to Finish the Tasks	1986	Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask	Medium
226	Range Addition II	598	Array, Math	Easy
227	Patching Array	330	Array, Greedy	Hard
228	Merge Two Sorted Lists	21	Linked List, Recursion	Easy
229	Palindrome Linked List	234	Linked List, Two Pointers, Stack, Recursion	Easy
230	Find Minimum in Rotated Sorted Array	153	Array, Binary Search	Medium
231	Linked List Cycle	141	Hash Table, Linked List, Two Pointers	Easy
232	Maximum Depth of Binary Tree	104	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Easy
233	Validate Binary Search Tree	98	Tree, Depth-First Search, Binary Search Tree, Binary Tree	Medium
234	Symmetric Tree	101	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Easy
235	Number of Strings That Appear as Substrings in Word	1967	String	Easy
236	Array Nesting	565	Array, Depth-First Search	Medium
237	Binary Tree Level Order Traversal	102	Tree, Breadth-First Search, Binary Tree	Medium
238	Convert Sorted Array to Binary Search Tree	108	Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree	Easy
239	Unique Binary Search Trees II	95	Dynamic Programming, Backtracking, Tree, Binary Search Tree, Binary Tree	Medium
240	Merge Sorted Array	88	Array, Two Pointers, Sorting	Easy
241	Sum of Distances in Tree	834	Dynamic Programming, Tree, Depth-First Search, Graph	Hard
242	First Bad Version	278	Binary Search, Interactive	Easy
243	Climbing Stairs	70	Math, Dynamic Programming, Memoization	Easy
244	Best Time to Buy and Sell Stock	121	Array, Dynamic Programming	Easy
245	Maximum Subarray	53	Array, Divide and Conquer, Dynamic Programming	Easy
246	House Robber	198	Array, Dynamic Programming	Medium
247	Shuffle an Array	384	Array, Math, Randomized	Medium
248	Find the Middle Index in Array	1991	Array, Prefix Sum	Easy
249	Find All Groups of Farmland	1992	Array, Depth-First Search, Breadth-First Search, Matrix	Medium
250	Operations on Tree	1993	Hash Table, Tree, Breadth-First Search, Design	Medium
251	Min Stack	155	Stack, Design	Easy
252	Orderly Queue	899	Math, String, Sorting	Hard
253	Slowest Key	1629	Array, String	Easy
254	Reverse Linked List	206	Linked List, Recursion	Easy
255	Fizz Buzz	412	Math, String, Simulation	Easy
256	Count Primes	204	Array, Math, Enumeration, Number Theory	Easy
257	Power of Three	326	Math, Recursion	Easy
258	Shifting Letters	848	Array, String	Medium
259	Roman to Integer	13	Hash Table, Math, String	Easy
260	Number of 1 Bits	191	Bit Manipulation	Easy
261	Hamming Distance	461	Bit Manipulation	Easy
262	Largest Plus Sign	764	Array, Dynamic Programming	Medium
263	Reverse Bits	190	Divide and Conquer, Bit Manipulation	Easy
264	Pascal's Triangle	118	Array, Dynamic Programming	Easy
265	Valid Parentheses	20	String, Stack	Easy
266	Missing Number	268	Array, Hash Table, Math, Bit Manipulation, Sorting	Easy
267	Basic Calculator	224	Math, String, Stack, Recursion	Hard
268	Arithmetic Slices II - Subsequence	446	Array, Dynamic Programming	Hard
269	Number of Pairs of Interchangeable Rectangles	2001		Medium
270	Smallest Missing Genetic Value in Each Subtree	2003		Hard
271	Maximum Product of the Length of Two Palindromic Subsequences	2002		Medium
272	Reverse Prefix of Word	2000		Easy
273	Count Special Quadruplets	1995	Array, Enumeration	Easy
274	First Day Where You Have Been in All the Rooms	1997	Array, Dynamic Programming	Medium
275	The Number of Weak Characters in the Game	1996	Array, Stack, Greedy, Sorting, Monotonic Stack	Medium
276	Maximum Number of Balloons	1189	Hash Table, String, Counting	Easy
277	Reverse Only Letters	917	Two Pointers, String	Easy
278	Number of Unique Good Subsequences	1987	String, Dynamic Programming	Hard
279	Longest Turbulent Subarray	978	Array, Dynamic Programming, Sliding Window	Medium
280	Spiral Matrix	54	Array, Matrix, Simulation	Medium
281	Expression Add Operators	282	Math, String, Backtracking	Hard
282	Count Number of Pairs With Absolute Difference K	2006	Array	Easy
283	Find Original Array From Doubled Array	2007	Array, Hash Table, Greedy, Sorting	Medium
284	Maximum Earnings From Taxi	2008	Array, Binary Search, Dynamic Programming, Sorting	Medium
285	Minimum Number of Operations to Make Array Continuous	2009	Array, Binary Search	Hard
286	Final Value of Variable After Performing Operations	2011	Array, String, Simulation	Easy
287	Sum of Beauty in the Array	2012	Array	Medium
288	Detect Squares	2013	Array, Hash Table, Design, Counting	Medium
289	Distinct Subsequences	115	String, Dynamic Programming	Hard
290	Find Winner on a Tic Tac Toe Game	1275	Array, Hash Table, Matrix, Simulation	Easy
291	Max Consecutive Ones	485	Array	Easy
292	3Sum	15	Array, Two Pointers, Sorting	Medium
293	Longest Substring Without Repeating Characters	3	Hash Table, String, Sliding Window	Medium
294	Longest Palindromic Substring	5	String, Dynamic Programming	Medium
295	Increasing Triplet Subsequence	334	Array, Greedy	Medium
296	Add Two Numbers	2	Linked List, Math, Recursion	Medium
297	Odd Even Linked List	328	Linked List	Medium
298	Intersection of Two Linked Lists	160	Hash Table, Linked List, Two Pointers	Easy
299	Maximum Length of a Concatenated String with Unique Characters	1239	Array, String, Backtracking, Bit Manipulation	Medium
300	GCD Sort of an Array	1998	Array, Math, Union Find, Sorting	Hard
301	Binary Tree Zigzag Level Order Traversal	103	Tree, Breadth-First Search, Binary Tree	Medium
302	Construct Binary Tree from Preorder and Inorder Traversal	105	Array, Hash Table, Divide and Conquer, Tree, Binary Tree	Medium
303	Kth Smallest Element in a BST	230	Tree, Depth-First Search, Binary Search Tree, Binary Tree	Medium
304	Binary Tree Inorder Traversal	94	Stack, Tree, Depth-First Search, Binary Tree	Easy
305	Number of Islands	200	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix	Medium
306	Letter Combinations of a Phone Number	17	Hash Table, String, Backtracking	Medium
307	Generate Parentheses	22	String, Dynamic Programming, Backtracking	Medium
308	Word Search	79	Array, Backtracking, Matrix	Medium
309	Break a Palindrome	1328	String, Greedy	Medium
310	N-th Tribonacci Number	1137	Math, Dynamic Programming, Memoization	Easy
311	Sort Colors	75	Array, Two Pointers, Sorting	Medium
312	Top K Frequent Elements	347	Array, Hash Table, Divide and Conquer, Sorting, Heap (Priority Queue), Bucket Sort, Counting, Quickselect	Medium
313	Shortest Path in a Grid with Obstacles Elimination	1293	Array, Breadth-First Search, Matrix	Hard
314	Maximum Difference Between Increasing Elements	2016	Array	Easy
315	Grid Game	2017	Array, Matrix, Prefix Sum	Medium
316	Check if Word Can Be Placed In Crossword	2018	Array, Matrix, Enumeration	Medium
317	Unique Email Addresses	929	Array, Hash Table, String	Easy
318	Sort Array By Parity II	922	Array, Two Pointers, Sorting	Easy
319	Partition to K Equal Sum Subsets	698	Array, Dynamic Programming, Backtracking, Bit Manipulation, Memoization, Bitmask	Medium
320	Split Linked List in Parts	725	Linked List	Medium
321	Longest Common Subsequence	1143	String, Dynamic Programming	Medium
322	Jump Game	55	Array, Dynamic Programming, Greedy	Medium
323	Dungeon Game	174	Array, Dynamic Programming, Matrix	Hard
324	Minimum Moves to Convert String	2027		Easy
325	Find Missing Observations	2028		Medium
326	Stone Game IX	2029		Medium
327	Subtree of Another Tree	572	Tree, Depth-First Search, String Matching, Binary Tree, Hash Function	Easy
328	Island Perimeter	463	Array, Depth-First Search, Breadth-First Search, Matrix	Easy
329	Longest Subsequence Repeated k Times	2014	String, Backtracking, Greedy, Counting, Enumeration	Hard
330	Find All Duplicates in an Array	442	Array, Hash Table	Medium
331	Kth Largest Element in an Array	215	Array, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect	Medium
332	Implement Trie (Prefix Tree)	208	Hash Table, String, Design, Trie	Medium
333	Find First and Last Position of Element in Sorted Array	34	Array, Binary Search	Medium
334	Search in Rotated Sorted Array	33	Array, Binary Search	Medium
335	Convert 1D Array Into 2D Array	2022	Array, Matrix, Simulation	Easy
336	Number of Pairs of Strings With Concatenation Equal to Target	2023	Array, String	Medium
337	Maximize the Confusion of an Exam	2024	String, Binary Search, Sliding Window, Prefix Sum	Medium
338	Max Consecutive Ones III	1004	Array, Binary Search, Sliding Window, Prefix Sum	Medium
339	Longest Repeating Character Replacement	424	Hash Table, String, Sliding Window	Medium
340	Maximum Number of Ways to Partition an Array	2025	Array, Hash Table, Counting, Enumeration, Prefix Sum	Hard
341	Word Search II	212	Array, String, Backtracking, Trie, Matrix	Hard
342	Two Out of Three	2032	Array, Hash Table	Easy
343	Minimum Operations to Make a Uni-Value Grid	2033	Array, Math, Sorting, Matrix	Medium
344	Stock Price Fluctuation	2034	Hash Table, Design, Heap (Priority Queue), Ordered Set	Medium
345	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Array, Two Pointers, Binary Search, Dynamic Programming, Bit Manipulation, Ordered Set, Bitmask	Hard
346	Diameter of Binary Tree	543	Tree, Depth-First Search, Binary Tree	Easy
347	Bitwise AND of Numbers Range	201	Bit Manipulation	Medium
348	Search a 2D Matrix II	240	Array, Binary Search, Divide and Conquer, Matrix	Medium
349	Guess Number Higher or Lower	374	Binary Search, Interactive	Easy
350	Unique Paths	62	Math, Dynamic Programming, Combinatorics	Medium
351	Coin Change	322	Array, Dynamic Programming, Breadth-First Search	Medium
352	Construct Binary Search Tree from Preorder Traversal	1008	Array, Stack, Tree, Binary Search Tree, Monotonic Stack, Binary Tree	Medium
353	Perfect Squares	279	Math, Dynamic Programming, Breadth-First Search	Medium
354	Best Time to Buy and Sell Stock with Cooldown	309	Array, Dynamic Programming	Medium
355	Minimum Number of Moves to Seat Everyone	2037	Array, Sorting	Easy
356	Remove Colored Pieces if Both Neighbors are the Same Color	2038	Math, String, Greedy, Game Theory	Medium
357	The Time When the Network Becomes Idle	2039	Array, Breadth-First Search, Graph	Medium
358	Check if Numbers Are Ascending in a Sentence	2042	String	Easy
359	Simple Bank System	2043	Array, Hash Table, Design, Simulation	Medium
360	Count Number of Maximum Bitwise-OR Subsets	2044	Array, Backtracking, Bit Manipulation	Medium
361	Second Minimum Time to Reach Destination	2045	Array, Breadth-First Search, Graph, Shortest Path	Hard
362	Path Sum III	437	Tree, Depth-First Search, Binary Tree	Medium
363	Cousins in Binary Tree	993	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Easy
364	Best Time to Buy and Sell Stock III	123	Array, Dynamic Programming	Hard
365	Happy Number	202	Hash Table, Math, Two Pointers	Easy
366	Factorial Trailing Zeroes	172	Math	Medium
367	Excel Sheet Column Number	171	Math, String	Easy
368	Pow(x, n)	50	Math, Recursion	Medium
369	Sqrt(x)	69	Math, Binary Search	Easy
370	Next Greater Element I	496	Array, Hash Table, Stack, Monotonic Stack	Easy
371	Sum of Two Integers	371	Math, Bit Manipulation	Medium
372	Reverse Words in a String	151	Two Pointers, String	Medium
373	Insert Delete GetRandom O(1)	380	Array, Hash Table, Math, Design, Randomized	Medium
374	Evaluate Reverse Polish Notation	150	Array, Math, Stack	Medium
375	Majority Element	169	Array, Hash Table, Divide and Conquer, Sorting, Counting	Easy
376	Sort Characters By Frequency	451	Hash Table, String, Sorting, Heap (Priority Queue), Bucket Sort, Counting	Medium
377	Task Scheduler	621	Array, Hash Table, Greedy, Sorting, Heap (Priority Queue), Counting	Medium
378	Find Minimum in Rotated Sorted Array II	154	Array, Binary Search	Hard
379	Number of Valid Words in a Sentence	2047		Easy
380	Next Greater Numerically Balanced Number	2048		Medium
381	Count Nodes With the Highest Score	2049		Medium
382	Parallel Courses III	2050		Hard
383	Count Complete Tree Nodes	222	Binary Search, Tree, Depth-First Search, Binary Tree	Medium
384	Invert Binary Tree	226	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Easy
385	Network Delay Time	743	Depth-First Search, Breadth-First Search, Graph, Heap (Priority Queue), Shortest Path	Medium
386	Path with Maximum Probability	1514	Graph, Heap (Priority Queue), Shortest Path	Medium
387	Path With Minimum Effort	1631	Array, Binary Search, Depth-First Search, Breadth-First Search, Union Find, Heap (Priority Queue), Matrix	Medium
388	Rotting Oranges	994	Array, Breadth-First Search, Matrix	Medium
389	Smallest Index With Equal Value	2057	Array	Easy
390	Find the Minimum and Maximum Number of Nodes Between Critical Points	2058	Linked List	Medium
391	Minimum Operations to Convert Number	2059	Array, Breadth-First Search	Medium
392	Surrounded Regions	130	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix	Medium
393	Sum Root to Leaf Numbers	129	Tree, Depth-First Search, Binary Tree	Medium
394	Sum of Left Leaves	404	Tree, Depth-First Search, Breadth-First Search, Binary Tree	Easy
395	Arranging Coins	441	Math, Binary Search	Easy
396	Kth Distinct String in an Array	2053	Array, Hash Table, String, Counting	Easy
397	Two Best Non-Overlapping Events	2054	Array, Binary Search, Dynamic Programming, Sorting, Heap (Priority Queue)	Medium
398	Plates Between Candles	2055	Array, String, Binary Search, Prefix Sum	Medium
399	Single Number III	260	Array, Bit Manipulation	Medium
400	Vowels of All Substrings	2063	Math, String, Dynamic Programming, Combinatorics	Medium
401	Minimized Maximum of Products Distributed to Any Store	2064	Array, Binary Search	Medium
402	Multiply Strings	43	Math, String, Simulation	Medium
403	Maximum Path Quality of a Graph	2065	Array, Backtracking, Graph	Hard
404	Unique Binary Search Trees	96	Math, Dynamic Programming, Tree, Binary Search Tree, Binary Tree	Medium
405	Number of Valid Words for Each Puzzle	1178	Array, Hash Table, String, Bit Manipulation, Trie	Hard
406	Minimum Value to Get Positive Step by Step Sum	1413	Array, Prefix Sum	Easy
407	First Missing Positive	41	Array, Hash Table	Hard
408	Remove Linked List Elements	203	Linked List, Recursion	Easy
409	Daily Temperatures	739	Array, Stack, Monotonic Stack	Medium
410	Guess the Word	843	Array, Math, String, Interactive, Game Theory	Hard
411	Check Whether Two Strings are Almost Equivalent	2068	Hash Table, String, Counting	Easy
412	Most Beautiful Item for Each Query	2070	Array, Binary Search, Sorting	Medium
413	Walking Robot Simulation II	2069	Design, Simulation	Medium
414	Time Needed to Buy Tickets	2073	Array, Queue, Simulation	Easy
415	Reverse Nodes in Even Length Groups	2074	Linked List	Medium
416	Decode the Slanted Ciphertext	2075	String, Simulation	Medium
417	Process Restricted Friend Requests	2076	Union Find, Graph	Hard
418	Iterator for Combination	1286	String, Backtracking, Design, Iterator	Medium
419	Expressive Words	809	Array, Two Pointers, String	Medium
420	Validate Stack Sequences	946	Array, Stack, Simulation	Medium
421	Largest Divisible Subset	368	Array, Math, Dynamic Programming, Sorting	Medium
422	Redundant Connection	684	Depth-First Search, Breadth-First Search, Union Find, Graph	Medium
423	Kth Smallest Number in Multiplication Table	668	Binary Search	Hard
424	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Array, Queue, Sliding Window, Heap (Priority Queue), Ordered Set, Monotonic Queue	Medium
425	Find All Numbers Disappeared in an Array	448	Array, Hash Table	Easy
426	Delete Nodes And Return Forest	1110	Tree, Depth-First Search, Binary Tree	Medium
427	Text Justification	68	Array, String, Simulation	Hard
428	Single Element in a Sorted Array	540	Array, Binary Search	Medium
429	Logger Rate Limiter	359	Hash Table, Design	Easy
430	Find Leaves of Binary Tree	366	Tree, Depth-First Search, Binary Tree	Medium
431	Construct Binary Tree from Inorder and Postorder Traversal	106	Array, Hash Table, Divide and Conquer, Tree, Binary Tree	Medium
432	Two Furthest Houses With Different Colors	2078		Easy
433	Watering Plants	2079	Array	Medium
434	Sum of k-Mirror Numbers	2081		Hard
435	Range Frequency Queries	2080	Array, Binary Search	Medium
436	Longest Absolute File Path	388	String, Stack, Depth-First Search	Medium
437	Decode String	394	String, Stack, Recursion	Medium
438	Delete Node in a BST	450	Tree, Binary Search Tree, Binary Tree	Medium
439	Count Vowel Substrings of a String	2062	Hash Table, String	Easy

Difficulty

Easy Questions

ID	Problem	Leetcode ID	Categories
1		429
2		116
3		297
4		430
5		284
6	Get Maximum in Generated Array	1646	Array, Dynamic Programming, Simulation
7	Design an Ordered Stream	1656	Array, Hash Table, Design, Data Stream
8	Check If Two String Arrays are Equivalent	1662	Array, String
9	Richest Customer Wealth	1672	Array, Matrix
10	Count of Matches in Tournament	1688	Math, Simulation
11	Determine if String Halves Are Alike	1704	String, Counting
12	Maximum Units on a Truck	1710	Array, Greedy, Sorting
13	Decode XORed Array	1720	Array, Bit Manipulation
14	Number Of Rectangles That Can Form The Largest Square	1725	Array
15	Latest Time by Replacing Hidden Digits	1736	String, Greedy
16	Maximum Number of Balls in a Box	1742	Hash Table, Math, Counting
17	Check if Array Is Sorted and Rotated	1752	Array
18	Minimum Changes To Make Alternating Binary String	1758	String
19	Merge Strings Alternately	1768	Two Pointers, String
20	Check if Binary String Has at Most One Segment of Ones	1784	String
21	Check if One String Swap Can Make Strings Equal	1790	Hash Table, String, Counting
22	Find Center of Star Graph	1791	Graph
23	Maximum Ascending Subarray Sum	1800	Array
24	Number of Different Integers in a String	1805	Hash Table, String
25	Truncate Sentence	1816	Array, String
26	Sign of the Product of an Array	1822	Array, Math
27	Check if the Sentence Is Pangram	1832	Hash Table, String
28	Sum of Digits in Base K	1837	Math
29	Minimum Distance to the Target Element	1848	Array
30	Longer Contiguous Segments of Ones than Zeros	1869	String
31	Maximum Population Year	1854	Array, Counting
32	Sum of All Subset XOR Totals	1863	Array, Backtracking, Bit Manipulation
33	Determine Whether Matrix Can Be Obtained By Rotation	1886	Array, Matrix
34	Redistribute Characters to Make All Strings Equal	1897	Hash Table, String, Counting
35	Check if Word Equals Summation of Two Words	1880	String
36	Largest Odd Number in String	1903	Math, String, Greedy
37	Maximum Product Difference Between Two Pairs	1913	Array, Sorting
38	Build Array from Permutation	1920	Array, Simulation
39	Reshape the Matrix	566	Array, Matrix, Simulation
40	Remove One Element to Make the Array Strictly Increasing	1909	Array
41	Concatenation of Array	1929	Array
42	Isomorphic Strings	205	Hash Table, String
43	Count Square Sum Triples	1925	Math, Enumeration
44	Maximum Number of Words You Can Type	1935	Hash Table, String
45	Sum of Digits of String After Convert	1945	String, Simulation
46	Check if All Characters Have Equal Number of Occurrences	1941	Hash Table, String, Counting
47	Three Divisors	1952	Math
48	Check If String Is a Prefix of Array	1961	Array, String
49	Add Strings	415	Math, String, Simulation
50	Range Sum Query - Immutable	303	Array, Design, Prefix Sum
51	Delete Characters to Make Fancy String	1957	String
52	Remove Duplicates from Sorted Array	26	Array, Two Pointers
53	Contains Duplicate	217	Array, Hash Table, Sorting
54	Single Number	136	Array, Bit Manipulation
55	Intersection of Two Arrays II	350	Array, Hash Table, Two Pointers, Binary Search, Sorting
56	Intersection of Two Arrays	349	Array, Hash Table, Two Pointers, Binary Search, Sorting
57	Plus One	66	Array, Math
58	Move Zeroes	283	Array, Two Pointers
59	Two Sum	1	Array, Hash Table
60	Reverse String	344	Two Pointers, String, Recursion
61	Reverse Integer	7	Math
62	First Unique Character in a String	387	Hash Table, String, Queue, Counting
63	Valid Anagram	242	Hash Table, String, Sorting
64	Valid Palindrome	125	Two Pointers, String
65	Implement strStr()	28	Two Pointers, String, String Matching
66	Minimum Time to Type Word Using Special Typewriter	1974	String, Greedy
67	Find Greatest Common Divisor of Array	1979	Array, Math
68	Two Sum IV - Input is a BST	653	Hash Table, Two Pointers, Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree
69	Longest Common Prefix	14	String
70	Delete Node in a Linked List	237	Linked List
71	Minimum Difference Between Highest and Lowest of K Scores	1984	Array, Sorting
72	Range Addition II	598	Array, Math
73	Merge Two Sorted Lists	21	Linked List, Recursion
74	Palindrome Linked List	234	Linked List, Two Pointers, Stack, Recursion
75	Linked List Cycle	141	Hash Table, Linked List, Two Pointers
76	Maximum Depth of Binary Tree	104	Tree, Depth-First Search, Breadth-First Search, Binary Tree
77	Symmetric Tree	101	Tree, Depth-First Search, Breadth-First Search, Binary Tree
78	Number of Strings That Appear as Substrings in Word	1967	String
79	Convert Sorted Array to Binary Search Tree	108	Array, Divide and Conquer, Tree, Binary Search Tree, Binary Tree
80	Merge Sorted Array	88	Array, Two Pointers, Sorting
81	First Bad Version	278	Binary Search, Interactive
82	Climbing Stairs	70	Math, Dynamic Programming, Memoization
83	Best Time to Buy and Sell Stock	121	Array, Dynamic Programming
84	Maximum Subarray	53	Array, Divide and Conquer, Dynamic Programming
85	Find the Middle Index in Array	1991	Array, Prefix Sum
86	Min Stack	155	Stack, Design
87	Slowest Key	1629	Array, String
88	Reverse Linked List	206	Linked List, Recursion
89	Fizz Buzz	412	Math, String, Simulation
90	Count Primes	204	Array, Math, Enumeration, Number Theory
91	Power of Three	326	Math, Recursion
92	Roman to Integer	13	Hash Table, Math, String
93	Number of 1 Bits	191	Bit Manipulation
94	Hamming Distance	461	Bit Manipulation
95	Reverse Bits	190	Divide and Conquer, Bit Manipulation
96	Pascal's Triangle	118	Array, Dynamic Programming
97	Valid Parentheses	20	String, Stack
98	Missing Number	268	Array, Hash Table, Math, Bit Manipulation, Sorting
99	Reverse Prefix of Word	2000
100	Count Special Quadruplets	1995	Array, Enumeration
101	Maximum Number of Balloons	1189	Hash Table, String, Counting
102	Reverse Only Letters	917	Two Pointers, String
103	Count Number of Pairs With Absolute Difference K	2006	Array
104	Final Value of Variable After Performing Operations	2011	Array, String, Simulation
105	Find Winner on a Tic Tac Toe Game	1275	Array, Hash Table, Matrix, Simulation
106	Max Consecutive Ones	485	Array
107	Intersection of Two Linked Lists	160	Hash Table, Linked List, Two Pointers
108	Binary Tree Inorder Traversal	94	Stack, Tree, Depth-First Search, Binary Tree
109	N-th Tribonacci Number	1137	Math, Dynamic Programming, Memoization
110	Maximum Difference Between Increasing Elements	2016	Array
111	Unique Email Addresses	929	Array, Hash Table, String
112	Sort Array By Parity II	922	Array, Two Pointers, Sorting
113	Minimum Moves to Convert String	2027
114	Subtree of Another Tree	572	Tree, Depth-First Search, String Matching, Binary Tree, Hash Function
115	Island Perimeter	463	Array, Depth-First Search, Breadth-First Search, Matrix
116	Convert 1D Array Into 2D Array	2022	Array, Matrix, Simulation
117	Two Out of Three	2032	Array, Hash Table
118	Diameter of Binary Tree	543	Tree, Depth-First Search, Binary Tree
119	Guess Number Higher or Lower	374	Binary Search, Interactive
120	Minimum Number of Moves to Seat Everyone	2037	Array, Sorting
121	Check if Numbers Are Ascending in a Sentence	2042	String
122	Cousins in Binary Tree	993	Tree, Depth-First Search, Breadth-First Search, Binary Tree
123	Happy Number	202	Hash Table, Math, Two Pointers
124	Excel Sheet Column Number	171	Math, String
125	Sqrt(x)	69	Math, Binary Search
126	Next Greater Element I	496	Array, Hash Table, Stack, Monotonic Stack
127	Majority Element	169	Array, Hash Table, Divide and Conquer, Sorting, Counting
128	Number of Valid Words in a Sentence	2047
129	Invert Binary Tree	226	Tree, Depth-First Search, Breadth-First Search, Binary Tree
130	Smallest Index With Equal Value	2057	Array
131	Sum of Left Leaves	404	Tree, Depth-First Search, Breadth-First Search, Binary Tree
132	Arranging Coins	441	Math, Binary Search
133	Kth Distinct String in an Array	2053	Array, Hash Table, String, Counting
134	Minimum Value to Get Positive Step by Step Sum	1413	Array, Prefix Sum
135	Remove Linked List Elements	203	Linked List, Recursion
136	Check Whether Two Strings are Almost Equivalent	2068	Hash Table, String, Counting
137	Time Needed to Buy Tickets	2073	Array, Queue, Simulation
138	Find All Numbers Disappeared in an Array	448	Array, Hash Table
139	Logger Rate Limiter	359	Hash Table, Design
140	Two Furthest Houses With Different Colors	2078
141	Count Vowel Substrings of a String	2062	Hash Table, String

Medium Questions

ID	Problem	Leetcode ID	Categories
1	Minimum Deletions to Make Character Frequencies Unique	1647	String, Greedy, Sorting
2	Sell Diminishing-Valued Colored Balls	1648	Array, Math, Binary Search, Greedy, Sorting, Heap (Priority Queue)
3	Determine if Two Strings Are Close	1657	Hash Table, String, Sorting
4	Smallest String With A Given Numeric Value	1663	String, Greedy
5	Find the Most Competitive Subsequence	1673	Array, Stack, Greedy, Monotonic Stack
6	Minimum Moves to Make Array Complementary	1674	Array, Hash Table, Prefix Sum
7	Partitioning Into Minimum Number Of Deci-Binary Numbers	1689	String, Greedy
8	Maximum Number of Eaten Apples	1705	Array, Greedy, Heap (Priority Queue)
9	Where Will the Ball Fall	1706	Array, Dynamic Programming, Depth-First Search, Matrix, Simulation
10	Count Good Meals	1711	Array, Hash Table
11	Swapping Nodes in a Linked List	1721	Linked List, Two Pointers
12	Minimize Hamming Distance After Swap Operations	1722	Array, Depth-First Search, Union Find
13	Tuple with Same Product	1726	Array, Hash Table
14	Largest Submatrix With Rearrangements	1727	Array, Greedy, Sorting, Matrix
15	Change Minimum Characters to Satisfy One of Three Conditions	1737	Hash Table, String, Counting, Prefix Sum
16	Find Kth Largest XOR Coordinate Value	1738	Array, Divide and Conquer, Bit Manipulation, Heap (Priority Queue), Matrix, Prefix Sum, Quickselect
17	Restore the Array From Adjacent Pairs	1743	Array, Hash Table
18	Count Number of Homogenous Substrings	1759	Math, String
19	Minimum Number of Operations to Move All Balls to Each Box	1769	Array, String
20	Maximum Score from Performing Multiplication Operations	1770	Array, Dynamic Programming
21	Maximum Average Pass Ratio	1792	Array, Greedy, Heap (Priority Queue)
22	Number of Orders in the Backlog	1801	Array, Heap (Priority Queue), Simulation
23	Finding the Users Active Minutes	1817	Array, Hash Table
24	Minimum Absolute Sum Difference	1818	Array, Binary Search, Sorting, Ordered Set
25	Find the Winner of the Circular Game	1823	Array, Math, Recursion, Queue, Simulation
26	Minimum Sideway Jumps	1824	Array, Dynamic Programming, Greedy
27	Maximum Ice Cream Bars	1833	Array, Greedy, Sorting
28	Single-Threaded CPU	1834	Array, Sorting, Heap (Priority Queue)
29	Frequency of the Most Frequent Element	1838	Array, Binary Search, Greedy, Sliding Window, Sorting, Prefix Sum
30	Longest Substring Of All Vowels in Order	1839	String, Sliding Window
31	Minimum Number of Swaps to Make the Binary String Alternating	1864	String, Greedy
32	Finding Pairs With a Certain Sum	1865	Array, Hash Table, Design
33	Splitting a String Into Descending Consecutive Values	1849	String, Backtracking
34	Next Permutation	31	Array, Two Pointers
35	Minimum Adjacent Swaps to Reach the Kth Smallest Number	1850	Two Pointers, String, Greedy
36	Maximum Distance Between a Pair of Values	1855	Array, Two Pointers, Binary Search, Greedy
37	Maximum Subarray Min-Product	1856	Array, Stack, Monotonic Stack, Prefix Sum
38	Minimum Speed to Arrive on Time	1870	Array, Binary Search
39	Jump Game VII	1871	Two Pointers, String, Prefix Sum
40	Process Tasks Using Servers	1882	Array, Heap (Priority Queue)
41	Merge Triplets to Form Target Triplet	1899	Array, Greedy
42	Maximum Value after Insertion	1881	String, Greedy
43	Count Sub Islands	1905	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix
44	Minimum Absolute Difference Queries	1906	Array, Hash Table
45	Reduction Operations to Make the Array Elements Equal	1887	Array, Sorting
46	Minimum Number of Flips to Make the Binary String Alternating	1888	String, Greedy
47	Cyclically Rotating a Grid	1914	Array, Matrix, Simulation
48	Number of Wonderful Substrings	1915	Hash Table, String, Bit Manipulation, Prefix Sum
49	Maximum Number of Removable Characters	1898	Array, String, Binary Search
50	Find K Closest Elements	658	Array, Two Pointers, Binary Search, Sorting, Heap (Priority Queue)
51	Eliminate Maximum Number of Monsters	1921	Array, Greedy, Sorting
52	Count Good Numbers	1922	Math, Recursion
53	Gray Code	89	Math, Backtracking, Bit Manipulation
54	Remove All Occurrences of a Substring	1910	String
55	Maximum Alternating Subsequence Sum	1911	Array, Dynamic Programming
56	Reduce Array Size to The Half	1338	Array, Hash Table, Greedy, Sorting, Heap (Priority Queue)
57	The Number of Full Rounds You Have Played	1904	Math, String
58	Kth Smallest Element in a Sorted Matrix	378	Array, Binary Search, Sorting, Heap (Priority Queue), Matrix
59	Maximum Length of Repeated Subarray	718	Array, Binary Search, Dynamic Programming, Sliding Window, Rolling Hash, Hash Function
60	Longest Increasing Subsequence	300	Array, Binary Search, Dynamic Programming
61	Unique Length-3 Palindromic Subsequences	1930	Hash Table, String, Prefix Sum
62	Custom Sort String	791	Hash Table, String, Sorting
63	Find Peak Element	162	Array, Binary Search
64	Valid Triangle Number	611	Array, Two Pointers, Binary Search, Greedy, Sorting
65	Sum Game	1927	Math, Greedy, Game Theory
66	Nearest Exit from Entrance in Maze	1926	Array, Breadth-First Search, Matrix
67	Add Minimum Number of Rungs	1936	Array, Greedy
68	Maximum Number of Points with Cost	1937	Array, Dynamic Programming
69	Push Dominoes	838	Two Pointers, String, Dynamic Programming
70	Partition Array into Disjoint Intervals	915	Array
71	Binary Tree Pruning	814	Tree, Depth-First Search, Binary Tree
72	Maximum Compatibility Score Sum	1947	Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask
73	3Sum Closest	16	Array, Two Pointers, Sorting
74	Beautiful Array	932	Array, Math, Divide and Conquer
75	01 Matrix	542	Array, Dynamic Programming, Breadth-First Search, Matrix
76	Map Sum Pairs	677	Hash Table, String, Design, Trie
77	The Number of the Smallest Unoccupied Chair	1942	Array, Heap (Priority Queue), Ordered Set
78	Describe the Painting	1943	Array, Prefix Sum
79	Minimum Garden Perimeter to Collect Enough Apples	1954	Math, Binary Search
80	Maximum Number of Weeks for Which You Can Work	1953	Array, Greedy
81	Subsets II	90	Array, Backtracking, Bit Manipulation
82	Path Sum II	113	Backtracking, Tree, Depth-First Search, Binary Tree
83	Combinations	77	Array, Backtracking
84	Permutations	46	Array, Backtracking
85	Permutations II	47	Array, Backtracking
86	Stone Game	877	Array, Math, Dynamic Programming, Game Theory
87	Subsets	78	Array, Backtracking, Bit Manipulation
88	Combination Sum	39	Array, Backtracking
89	Combination Sum II	40	Array, Backtracking
90	Remove Stones to Minimize the Total	1962	Array, Heap (Priority Queue)
91	Minimum Number of Swaps to Make the String Balanced	1963	Two Pointers, String, Stack, Greedy
92	Largest Number After Mutating Substring	1946	Array, String, Greedy
93	Flip String to Monotone Increasing	926	String, Dynamic Programming
94	Array of Doubled Pairs	954	Array, Hash Table, Greedy, Sorting
95	Group Anagrams	49	Hash Table, String, Sorting
96	Set Matrix Zeroes	73	Array, Hash Table, Matrix
97	Array With Elements Not Equal to Average of Neighbors	1968	Array, Greedy, Sorting
98	Minimum Non-Zero Product of the Array Elements	1969	Math, Greedy, Recursion
99	Count Good Nodes in Binary Tree	1448	Tree, Depth-First Search, Breadth-First Search, Binary Tree
100	Check if Move is Legal	1958	Array, Matrix, Enumeration
101	Minimum Total Space Wasted With K Resizing Operations	1959	Array, Dynamic Programming
102	Decode Ways	91	String, Dynamic Programming
103	Best Time to Buy and Sell Stock II	122	Array, Dynamic Programming, Greedy
104	Rotate Array	189	Array, Math, Two Pointers
105	Maximum Product of Splitted Binary Tree	1339	Tree, Depth-First Search, Binary Tree
106	Rotate Image	48	Array, Math, Matrix
107	Valid Sudoku	36	Array, Hash Table, Matrix
108	String to Integer (atoi)	8	String
109	Maximum Matrix Sum	1975	Array, Greedy, Matrix
110	Find Unique Binary String	1980	Array, String, Backtracking
111	Minimize the Difference Between Target and Chosen Elements	1981	Array, Dynamic Programming, Matrix
112	Merge Intervals	56	Array, Sorting
113	Complex Number Multiplication	537	Math, String, Simulation
114	Count and Say	38	String
115	Sum of Square Numbers	633	Math, Two Pointers, Binary Search
116	Remove Nth Node From End of List	19	Linked List, Two Pointers
117	Verify Preorder Serialization of a Binary Tree	331	String, Stack, Tree, Binary Tree
118	Longest Uncommon Subsequence II	522	Array, Hash Table, Two Pointers, String, Sorting
119	Find the Kth Largest Integer in the Array	1985	Array, String, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect
120	Minimum Number of Work Sessions to Finish the Tasks	1986	Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask
121	Find Minimum in Rotated Sorted Array	153	Array, Binary Search
122	Validate Binary Search Tree	98	Tree, Depth-First Search, Binary Search Tree, Binary Tree
123	Array Nesting	565	Array, Depth-First Search
124	Binary Tree Level Order Traversal	102	Tree, Breadth-First Search, Binary Tree
125	Unique Binary Search Trees II	95	Dynamic Programming, Backtracking, Tree, Binary Search Tree, Binary Tree
126	House Robber	198	Array, Dynamic Programming
127	Shuffle an Array	384	Array, Math, Randomized
128	Find All Groups of Farmland	1992	Array, Depth-First Search, Breadth-First Search, Matrix
129	Operations on Tree	1993	Hash Table, Tree, Breadth-First Search, Design
130	Shifting Letters	848	Array, String
131	Largest Plus Sign	764	Array, Dynamic Programming
132	Number of Pairs of Interchangeable Rectangles	2001
133	Maximum Product of the Length of Two Palindromic Subsequences	2002
134	First Day Where You Have Been in All the Rooms	1997	Array, Dynamic Programming
135	The Number of Weak Characters in the Game	1996	Array, Stack, Greedy, Sorting, Monotonic Stack
136	Longest Turbulent Subarray	978	Array, Dynamic Programming, Sliding Window
137	Spiral Matrix	54	Array, Matrix, Simulation
138	Find Original Array From Doubled Array	2007	Array, Hash Table, Greedy, Sorting
139	Maximum Earnings From Taxi	2008	Array, Binary Search, Dynamic Programming, Sorting
140	Sum of Beauty in the Array	2012	Array
141	Detect Squares	2013	Array, Hash Table, Design, Counting
142	3Sum	15	Array, Two Pointers, Sorting
143	Longest Substring Without Repeating Characters	3	Hash Table, String, Sliding Window
144	Longest Palindromic Substring	5	String, Dynamic Programming
145	Increasing Triplet Subsequence	334	Array, Greedy
146	Add Two Numbers	2	Linked List, Math, Recursion
147	Odd Even Linked List	328	Linked List
148	Maximum Length of a Concatenated String with Unique Characters	1239	Array, String, Backtracking, Bit Manipulation
149	Binary Tree Zigzag Level Order Traversal	103	Tree, Breadth-First Search, Binary Tree
150	Construct Binary Tree from Preorder and Inorder Traversal	105	Array, Hash Table, Divide and Conquer, Tree, Binary Tree
151	Kth Smallest Element in a BST	230	Tree, Depth-First Search, Binary Search Tree, Binary Tree
152	Number of Islands	200	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix
153	Letter Combinations of a Phone Number	17	Hash Table, String, Backtracking
154	Generate Parentheses	22	String, Dynamic Programming, Backtracking
155	Word Search	79	Array, Backtracking, Matrix
156	Break a Palindrome	1328	String, Greedy
157	Sort Colors	75	Array, Two Pointers, Sorting
158	Top K Frequent Elements	347	Array, Hash Table, Divide and Conquer, Sorting, Heap (Priority Queue), Bucket Sort, Counting, Quickselect
159	Grid Game	2017	Array, Matrix, Prefix Sum
160	Check if Word Can Be Placed In Crossword	2018	Array, Matrix, Enumeration
161	Partition to K Equal Sum Subsets	698	Array, Dynamic Programming, Backtracking, Bit Manipulation, Memoization, Bitmask
162	Split Linked List in Parts	725	Linked List
163	Longest Common Subsequence	1143	String, Dynamic Programming
164	Jump Game	55	Array, Dynamic Programming, Greedy
165	Find Missing Observations	2028
166	Stone Game IX	2029
167	Find All Duplicates in an Array	442	Array, Hash Table
168	Kth Largest Element in an Array	215	Array, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect
169	Implement Trie (Prefix Tree)	208	Hash Table, String, Design, Trie
170	Find First and Last Position of Element in Sorted Array	34	Array, Binary Search
171	Search in Rotated Sorted Array	33	Array, Binary Search
172	Number of Pairs of Strings With Concatenation Equal to Target	2023	Array, String
173	Maximize the Confusion of an Exam	2024	String, Binary Search, Sliding Window, Prefix Sum
174	Max Consecutive Ones III	1004	Array, Binary Search, Sliding Window, Prefix Sum
175	Longest Repeating Character Replacement	424	Hash Table, String, Sliding Window
176	Minimum Operations to Make a Uni-Value Grid	2033	Array, Math, Sorting, Matrix
177	Stock Price Fluctuation	2034	Hash Table, Design, Heap (Priority Queue), Ordered Set
178	Bitwise AND of Numbers Range	201	Bit Manipulation
179	Search a 2D Matrix II	240	Array, Binary Search, Divide and Conquer, Matrix
180	Unique Paths	62	Math, Dynamic Programming, Combinatorics
181	Coin Change	322	Array, Dynamic Programming, Breadth-First Search
182	Construct Binary Search Tree from Preorder Traversal	1008	Array, Stack, Tree, Binary Search Tree, Monotonic Stack, Binary Tree
183	Perfect Squares	279	Math, Dynamic Programming, Breadth-First Search
184	Best Time to Buy and Sell Stock with Cooldown	309	Array, Dynamic Programming
185	Remove Colored Pieces if Both Neighbors are the Same Color	2038	Math, String, Greedy, Game Theory
186	The Time When the Network Becomes Idle	2039	Array, Breadth-First Search, Graph
187	Simple Bank System	2043	Array, Hash Table, Design, Simulation
188	Count Number of Maximum Bitwise-OR Subsets	2044	Array, Backtracking, Bit Manipulation
189	Path Sum III	437	Tree, Depth-First Search, Binary Tree
190	Factorial Trailing Zeroes	172	Math
191	Pow(x, n)	50	Math, Recursion
192	Sum of Two Integers	371	Math, Bit Manipulation
193	Reverse Words in a String	151	Two Pointers, String
194	Insert Delete GetRandom O(1)	380	Array, Hash Table, Math, Design, Randomized
195	Evaluate Reverse Polish Notation	150	Array, Math, Stack
196	Sort Characters By Frequency	451	Hash Table, String, Sorting, Heap (Priority Queue), Bucket Sort, Counting
197	Task Scheduler	621	Array, Hash Table, Greedy, Sorting, Heap (Priority Queue), Counting
198	Next Greater Numerically Balanced Number	2048
199	Count Nodes With the Highest Score	2049
200	Count Complete Tree Nodes	222	Binary Search, Tree, Depth-First Search, Binary Tree
201	Network Delay Time	743	Depth-First Search, Breadth-First Search, Graph, Heap (Priority Queue), Shortest Path
202	Path with Maximum Probability	1514	Graph, Heap (Priority Queue), Shortest Path
203	Path With Minimum Effort	1631	Array, Binary Search, Depth-First Search, Breadth-First Search, Union Find, Heap (Priority Queue), Matrix
204	Rotting Oranges	994	Array, Breadth-First Search, Matrix
205	Find the Minimum and Maximum Number of Nodes Between Critical Points	2058	Linked List
206	Minimum Operations to Convert Number	2059	Array, Breadth-First Search
207	Surrounded Regions	130	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix
208	Sum Root to Leaf Numbers	129	Tree, Depth-First Search, Binary Tree
209	Two Best Non-Overlapping Events	2054	Array, Binary Search, Dynamic Programming, Sorting, Heap (Priority Queue)
210	Plates Between Candles	2055	Array, String, Binary Search, Prefix Sum
211	Single Number III	260	Array, Bit Manipulation
212	Vowels of All Substrings	2063	Math, String, Dynamic Programming, Combinatorics
213	Minimized Maximum of Products Distributed to Any Store	2064	Array, Binary Search
214	Multiply Strings	43	Math, String, Simulation
215	Unique Binary Search Trees	96	Math, Dynamic Programming, Tree, Binary Search Tree, Binary Tree
216	Daily Temperatures	739	Array, Stack, Monotonic Stack
217	Most Beautiful Item for Each Query	2070	Array, Binary Search, Sorting
218	Walking Robot Simulation II	2069	Design, Simulation
219	Reverse Nodes in Even Length Groups	2074	Linked List
220	Decode the Slanted Ciphertext	2075	String, Simulation
221	Iterator for Combination	1286	String, Backtracking, Design, Iterator
222	Expressive Words	809	Array, Two Pointers, String
223	Validate Stack Sequences	946	Array, Stack, Simulation
224	Largest Divisible Subset	368	Array, Math, Dynamic Programming, Sorting
225	Redundant Connection	684	Depth-First Search, Breadth-First Search, Union Find, Graph
226	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Array, Queue, Sliding Window, Heap (Priority Queue), Ordered Set, Monotonic Queue
227	Delete Nodes And Return Forest	1110	Tree, Depth-First Search, Binary Tree
228	Single Element in a Sorted Array	540	Array, Binary Search
229	Find Leaves of Binary Tree	366	Tree, Depth-First Search, Binary Tree
230	Construct Binary Tree from Inorder and Postorder Traversal	106	Array, Hash Table, Divide and Conquer, Tree, Binary Tree
231	Watering Plants	2079	Array
232	Range Frequency Queries	2080	Array, Binary Search
233	Longest Absolute File Path	388	String, Stack, Depth-First Search
234	Decode String	394	String, Stack, Recursion
235	Delete Node in a BST	450	Tree, Binary Search Tree, Binary Tree

Hard Questions

ID	Problem	Leetcode ID	Categories
1	Find Minimum Time to Finish All Jobs	1723	Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask
2	Building Boxes	1739	Math, Binary Search, Greedy
3	Minimum Degree of a Connected Trio in a Graph	1761	Graph
4	Maximize Palindrome Length From Subsequences	1771	String, Dynamic Programming
5	Number of Different Subsequences GCDs	1819	Array, Math, Counting, Number Theory
6	Finding MK Average	1825	Design, Queue, Heap (Priority Queue), Ordered Set
7	Find XOR Sum of All Pairs Bitwise AND	1835	Array, Math, Bit Manipulation
8	Maximum Building Height	1840	Array, Math
9	Minimum Interval to Include Each Query	1851	Array, Binary Search, Line Sweep, Sorting, Heap (Priority Queue)
10	Largest Color Value in a Directed Graph	1857	Hash Table, Dynamic Programming, Graph, Topological Sort, Memoization, Counting
11	Number of Ways to Rearrange Sticks With K Sticks Visible	1866	Math, Dynamic Programming, Combinatorics
12	Stone Game VIII	1872	Array, Math, Dynamic Programming, Prefix Sum, Game Theory
13	Minimum Skips to Arrive at Meeting On Time	1883	Array, Dynamic Programming
14	Minimum Space Wasted From Packaging	1889	Array, Binary Search, Sorting, Prefix Sum
15	Count Ways to Build Rooms in an Ant Colony	1916	Math, Dynamic Programming, Tree, Graph, Topological Sort, Combinatorics
16	Max Sum of Rectangle No Larger Than K	363	Array, Binary Search, Dynamic Programming, Matrix, Ordered Set
17	Count Vowels Permutation	1220	Dynamic Programming
18	Painting a Grid With Three Different Colors	1931	Dynamic Programming
19	Merge BSTs to Create Single BST	1932	Hash Table, Binary Search, Tree, Depth-First Search, Binary Tree
20	Three Equal Parts	927	Array, Math
21	Non-negative Integers without Consecutive Ones	600	Dynamic Programming
22	Number of Visible People in a Queue	1944	Array, Stack, Monotonic Stack
23	Trapping Rain Water	42	Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack
24	Count Number of Special Subsequences	1955	Array, Dynamic Programming
25	Making A Large Island	827	Array, Depth-First Search, Breadth-First Search, Union Find, Matrix
26	Palindrome Partitioning II	132	String, Dynamic Programming
27	Find the Longest Valid Obstacle Course at Each Position	1964	Array, Binary Search, Binary Indexed Tree
28	Word Ladder II	126	Hash Table, String, Backtracking, Breadth-First Search
29	Remove Boxes	546	Array, Dynamic Programming, Memoization
30	Last Day Where You Can Still Cross	1970	Array, Binary Search, Depth-First Search, Breadth-First Search, Union Find, Matrix
31	Minimum Window Substring	76	Hash Table, String, Sliding Window
32	Sudoku Solver	37	Array, Backtracking, Matrix
33	Rectangle Area II	850	Array, Segment Tree, Line Sweep, Ordered Set
34	Maximum Profit in Job Scheduling	1235	Array, Binary Search, Dynamic Programming, Sorting
35	Patching Array	330	Array, Greedy
36	Sum of Distances in Tree	834	Dynamic Programming, Tree, Depth-First Search, Graph
37	Orderly Queue	899	Math, String, Sorting
38	Basic Calculator	224	Math, String, Stack, Recursion
39	Arithmetic Slices II - Subsequence	446	Array, Dynamic Programming
40	Smallest Missing Genetic Value in Each Subtree	2003
41	Number of Unique Good Subsequences	1987	String, Dynamic Programming
42	Expression Add Operators	282	Math, String, Backtracking
43	Minimum Number of Operations to Make Array Continuous	2009	Array, Binary Search
44	Distinct Subsequences	115	String, Dynamic Programming
45	GCD Sort of an Array	1998	Array, Math, Union Find, Sorting
46	Shortest Path in a Grid with Obstacles Elimination	1293	Array, Breadth-First Search, Matrix
47	Dungeon Game	174	Array, Dynamic Programming, Matrix
48	Longest Subsequence Repeated k Times	2014	String, Backtracking, Greedy, Counting, Enumeration
49	Maximum Number of Ways to Partition an Array	2025	Array, Hash Table, Counting, Enumeration, Prefix Sum
50	Word Search II	212	Array, String, Backtracking, Trie, Matrix
51	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Array, Two Pointers, Binary Search, Dynamic Programming, Bit Manipulation, Ordered Set, Bitmask
52	Second Minimum Time to Reach Destination	2045	Array, Breadth-First Search, Graph, Shortest Path
53	Best Time to Buy and Sell Stock III	123	Array, Dynamic Programming
54	Find Minimum in Rotated Sorted Array II	154	Array, Binary Search
55	Parallel Courses III	2050
56	Maximum Path Quality of a Graph	2065	Array, Backtracking, Graph
57	Number of Valid Words for Each Puzzle	1178	Array, Hash Table, String, Bit Manipulation, Trie
58	First Missing Positive	41	Array, Hash Table
59	Guess the Word	843	Array, Math, String, Interactive, Game Theory
60	Process Restricted Friend Requests	2076	Union Find, Graph
61	Kth Smallest Number in Multiplication Table	668	Binary Search
62	Text Justification	68	Array, String, Simulation
63	Sum of k-Mirror Numbers	2081

Categories

Array

ID	Problem	Leetcode ID	Difficulty
1	Get Maximum in Generated Array	1646	Easy
2	Sell Diminishing-Valued Colored Balls	1648	Medium
3	Design an Ordered Stream	1656	Easy
4	Check If Two String Arrays are Equivalent	1662	Easy
5	Richest Customer Wealth	1672	Easy
6	Find the Most Competitive Subsequence	1673	Medium
7	Minimum Moves to Make Array Complementary	1674	Medium
8	Maximum Number of Eaten Apples	1705	Medium
9	Where Will the Ball Fall	1706	Medium
10	Maximum Units on a Truck	1710	Easy
11	Count Good Meals	1711	Medium
12	Decode XORed Array	1720	Easy
13	Minimize Hamming Distance After Swap Operations	1722	Medium
14	Find Minimum Time to Finish All Jobs	1723	Hard
15	Number Of Rectangles That Can Form The Largest Square	1725	Easy
16	Tuple with Same Product	1726	Medium
17	Largest Submatrix With Rearrangements	1727	Medium
18	Find Kth Largest XOR Coordinate Value	1738	Medium
19	Restore the Array From Adjacent Pairs	1743	Medium
20	Check if Array Is Sorted and Rotated	1752	Easy
21	Minimum Number of Operations to Move All Balls to Each Box	1769	Medium
22	Maximum Score from Performing Multiplication Operations	1770	Medium
23	Maximum Average Pass Ratio	1792	Medium
24	Maximum Ascending Subarray Sum	1800	Easy
25	Number of Orders in the Backlog	1801	Medium
26	Truncate Sentence	1816	Easy
27	Finding the Users Active Minutes	1817	Medium
28	Minimum Absolute Sum Difference	1818	Medium
29	Number of Different Subsequences GCDs	1819	Hard
30	Sign of the Product of an Array	1822	Easy
31	Find the Winner of the Circular Game	1823	Medium
32	Minimum Sideway Jumps	1824	Medium
33	Maximum Ice Cream Bars	1833	Medium
34	Single-Threaded CPU	1834	Medium
35	Find XOR Sum of All Pairs Bitwise AND	1835	Hard
36	Frequency of the Most Frequent Element	1838	Medium
37	Maximum Building Height	1840	Hard
38	Minimum Interval to Include Each Query	1851	Hard
39	Finding Pairs With a Certain Sum	1865	Medium
40	Minimum Distance to the Target Element	1848	Easy
41	Next Permutation	31	Medium
42	Maximum Distance Between a Pair of Values	1855	Medium
43	Maximum Subarray Min-Product	1856	Medium
44	Minimum Speed to Arrive on Time	1870	Medium
45	Maximum Population Year	1854	Easy
46	Process Tasks Using Servers	1882	Medium
47	Sum of All Subset XOR Totals	1863	Easy
48	Determine Whether Matrix Can Be Obtained By Rotation	1886	Easy
49	Stone Game VIII	1872	Hard
50	Merge Triplets to Form Target Triplet	1899	Medium
51	Minimum Skips to Arrive at Meeting On Time	1883	Hard
52	Count Sub Islands	1905	Medium
53	Minimum Absolute Difference Queries	1906	Medium
54	Reduction Operations to Make the Array Elements Equal	1887	Medium
55	Minimum Space Wasted From Packaging	1889	Hard
56	Maximum Product Difference Between Two Pairs	1913	Easy
57	Cyclically Rotating a Grid	1914	Medium
58	Maximum Number of Removable Characters	1898	Medium
59	Find K Closest Elements	658	Medium
60	Max Sum of Rectangle No Larger Than K	363	Hard
61	Build Array from Permutation	1920	Easy
62	Eliminate Maximum Number of Monsters	1921	Medium
63	Reshape the Matrix	566	Easy
64	Remove One Element to Make the Array Strictly Increasing	1909	Easy
65	Maximum Alternating Subsequence Sum	1911	Medium
66	Reduce Array Size to The Half	1338	Medium
67	Kth Smallest Element in a Sorted Matrix	378	Medium
68	Maximum Length of Repeated Subarray	718	Medium
69	Longest Increasing Subsequence	300	Medium
70	Concatenation of Array	1929	Easy
71	Find Peak Element	162	Medium
72	Valid Triangle Number	611	Medium
73	Nearest Exit from Entrance in Maze	1926	Medium
74	Three Equal Parts	927	Hard
75	Add Minimum Number of Rungs	1936	Medium
76	Maximum Number of Points with Cost	1937	Medium
77	Partition Array into Disjoint Intervals	915	Medium
78	Maximum Compatibility Score Sum	1947	Medium
79	3Sum Closest	16	Medium
80	Beautiful Array	932	Medium
81	01 Matrix	542	Medium
82	The Number of the Smallest Unoccupied Chair	1942	Medium
83	Describe the Painting	1943	Medium
84	Number of Visible People in a Queue	1944	Hard
85	Trapping Rain Water	42	Hard
86	Count Number of Special Subsequences	1955	Hard
87	Maximum Number of Weeks for Which You Can Work	1953	Medium
88	Making A Large Island	827	Hard
89	Subsets II	90	Medium
90	Combinations	77	Medium
91	Permutations	46	Medium
92	Permutations II	47	Medium
93	Stone Game	877	Medium
94	Subsets	78	Medium
95	Combination Sum	39	Medium
96	Combination Sum II	40	Medium
97	Remove Stones to Minimize the Total	1962	Medium
98	Find the Longest Valid Obstacle Course at Each Position	1964	Hard
99	Check If String Is a Prefix of Array	1961	Easy
100	Largest Number After Mutating Substring	1946	Medium
101	Array of Doubled Pairs	954	Medium
102	Set Matrix Zeroes	73	Medium
103	Remove Boxes	546	Hard
104	Array With Elements Not Equal to Average of Neighbors	1968	Medium
105	Last Day Where You Can Still Cross	1970	Hard
106	Range Sum Query - Immutable	303	Easy
107	Check if Move is Legal	1958	Medium
108	Minimum Total Space Wasted With K Resizing Operations	1959	Medium
109	Remove Duplicates from Sorted Array	26	Easy
110	Best Time to Buy and Sell Stock II	122	Medium
111	Rotate Array	189	Medium
112	Contains Duplicate	217	Easy
113	Single Number	136	Easy
114	Intersection of Two Arrays II	350	Easy
115	Intersection of Two Arrays	349	Easy
116	Plus One	66	Easy
117	Move Zeroes	283	Easy
118	Two Sum	1	Easy
119	Rotate Image	48	Medium
120	Valid Sudoku	36	Medium
121	Maximum Matrix Sum	1975	Medium
122	Find Greatest Common Divisor of Array	1979	Easy
123	Find Unique Binary String	1980	Medium
124	Minimize the Difference Between Target and Chosen Elements	1981	Medium
125	Sudoku Solver	37	Hard
126	Merge Intervals	56	Medium
127	Rectangle Area II	850	Hard
128	Longest Uncommon Subsequence II	522	Medium
129	Minimum Difference Between Highest and Lowest of K Scores	1984	Easy
130	Find the Kth Largest Integer in the Array	1985	Medium
131	Maximum Profit in Job Scheduling	1235	Hard
132	Minimum Number of Work Sessions to Finish the Tasks	1986	Medium
133	Range Addition II	598	Easy
134	Patching Array	330	Hard
135	Find Minimum in Rotated Sorted Array	153	Medium
136	Array Nesting	565	Medium
137	Convert Sorted Array to Binary Search Tree	108	Easy
138	Merge Sorted Array	88	Easy
139	Best Time to Buy and Sell Stock	121	Easy
140	Maximum Subarray	53	Easy
141	House Robber	198	Medium
142	Shuffle an Array	384	Medium
143	Find the Middle Index in Array	1991	Easy
144	Find All Groups of Farmland	1992	Medium
145	Slowest Key	1629	Easy
146	Count Primes	204	Easy
147	Shifting Letters	848	Medium
148	Largest Plus Sign	764	Medium
149	Pascal's Triangle	118	Easy
150	Missing Number	268	Easy
151	Arithmetic Slices II - Subsequence	446	Hard
152	Count Special Quadruplets	1995	Easy
153	First Day Where You Have Been in All the Rooms	1997	Medium
154	The Number of Weak Characters in the Game	1996	Medium
155	Longest Turbulent Subarray	978	Medium
156	Spiral Matrix	54	Medium
157	Count Number of Pairs With Absolute Difference K	2006	Easy
158	Find Original Array From Doubled Array	2007	Medium
159	Maximum Earnings From Taxi	2008	Medium
160	Minimum Number of Operations to Make Array Continuous	2009	Hard
161	Final Value of Variable After Performing Operations	2011	Easy
162	Sum of Beauty in the Array	2012	Medium
163	Detect Squares	2013	Medium
164	Find Winner on a Tic Tac Toe Game	1275	Easy
165	Max Consecutive Ones	485	Easy
166	3Sum	15	Medium
167	Increasing Triplet Subsequence	334	Medium
168	Maximum Length of a Concatenated String with Unique Characters	1239	Medium
169	GCD Sort of an Array	1998	Hard
170	Construct Binary Tree from Preorder and Inorder Traversal	105	Medium
171	Number of Islands	200	Medium
172	Word Search	79	Medium
173	Sort Colors	75	Medium
174	Top K Frequent Elements	347	Medium
175	Shortest Path in a Grid with Obstacles Elimination	1293	Hard
176	Maximum Difference Between Increasing Elements	2016	Easy
177	Grid Game	2017	Medium
178	Check if Word Can Be Placed In Crossword	2018	Medium
179	Unique Email Addresses	929	Easy
180	Sort Array By Parity II	922	Easy
181	Partition to K Equal Sum Subsets	698	Medium
182	Jump Game	55	Medium
183	Dungeon Game	174	Hard
184	Island Perimeter	463	Easy
185	Find All Duplicates in an Array	442	Medium
186	Kth Largest Element in an Array	215	Medium
187	Find First and Last Position of Element in Sorted Array	34	Medium
188	Search in Rotated Sorted Array	33	Medium
189	Convert 1D Array Into 2D Array	2022	Easy
190	Number of Pairs of Strings With Concatenation Equal to Target	2023	Medium
191	Max Consecutive Ones III	1004	Medium
192	Maximum Number of Ways to Partition an Array	2025	Hard
193	Word Search II	212	Hard
194	Two Out of Three	2032	Easy
195	Minimum Operations to Make a Uni-Value Grid	2033	Medium
196	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard
197	Search a 2D Matrix II	240	Medium
198	Coin Change	322	Medium
199	Construct Binary Search Tree from Preorder Traversal	1008	Medium
200	Best Time to Buy and Sell Stock with Cooldown	309	Medium
201	Minimum Number of Moves to Seat Everyone	2037	Easy
202	The Time When the Network Becomes Idle	2039	Medium
203	Simple Bank System	2043	Medium
204	Count Number of Maximum Bitwise-OR Subsets	2044	Medium
205	Second Minimum Time to Reach Destination	2045	Hard
206	Best Time to Buy and Sell Stock III	123	Hard
207	Next Greater Element I	496	Easy
208	Insert Delete GetRandom O(1)	380	Medium
209	Evaluate Reverse Polish Notation	150	Medium
210	Majority Element	169	Easy
211	Task Scheduler	621	Medium
212	Find Minimum in Rotated Sorted Array II	154	Hard
213	Path With Minimum Effort	1631	Medium
214	Rotting Oranges	994	Medium
215	Smallest Index With Equal Value	2057	Easy
216	Minimum Operations to Convert Number	2059	Medium
217	Surrounded Regions	130	Medium
218	Kth Distinct String in an Array	2053	Easy
219	Two Best Non-Overlapping Events	2054	Medium
220	Plates Between Candles	2055	Medium
221	Single Number III	260	Medium
222	Minimized Maximum of Products Distributed to Any Store	2064	Medium
223	Maximum Path Quality of a Graph	2065	Hard
224	Number of Valid Words for Each Puzzle	1178	Hard
225	Minimum Value to Get Positive Step by Step Sum	1413	Easy
226	First Missing Positive	41	Hard
227	Daily Temperatures	739	Medium
228	Guess the Word	843	Hard
229	Most Beautiful Item for Each Query	2070	Medium
230	Time Needed to Buy Tickets	2073	Easy
231	Expressive Words	809	Medium
232	Validate Stack Sequences	946	Medium
233	Largest Divisible Subset	368	Medium
234	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Medium
235	Find All Numbers Disappeared in an Array	448	Easy
236	Text Justification	68	Hard
237	Single Element in a Sorted Array	540	Medium
238	Construct Binary Tree from Inorder and Postorder Traversal	106	Medium
239	Watering Plants	2079	Medium
240	Range Frequency Queries	2080	Medium

Backtracking

ID	Problem	Leetcode ID	Difficulty
1	Find Minimum Time to Finish All Jobs	1723	Hard
2	Splitting a String Into Descending Consecutive Values	1849	Medium
3	Sum of All Subset XOR Totals	1863	Easy
4	Gray Code	89	Medium
5	Maximum Compatibility Score Sum	1947	Medium
6	Subsets II	90	Medium
7	Path Sum II	113	Medium
8	Combinations	77	Medium
9	Permutations	46	Medium
10	Permutations II	47	Medium
11	Subsets	78	Medium
12	Combination Sum	39	Medium
13	Combination Sum II	40	Medium
14	Word Ladder II	126	Hard
15	Find Unique Binary String	1980	Medium
16	Sudoku Solver	37	Hard
17	Minimum Number of Work Sessions to Finish the Tasks	1986	Medium
18	Unique Binary Search Trees II	95	Medium
19	Expression Add Operators	282	Hard
20	Maximum Length of a Concatenated String with Unique Characters	1239	Medium
21	Letter Combinations of a Phone Number	17	Medium
22	Generate Parentheses	22	Medium
23	Word Search	79	Medium
24	Partition to K Equal Sum Subsets	698	Medium
25	Longest Subsequence Repeated k Times	2014	Hard
26	Word Search II	212	Hard
27	Count Number of Maximum Bitwise-OR Subsets	2044	Medium
28	Maximum Path Quality of a Graph	2065	Hard
29	Iterator for Combination	1286	Medium

Binary Indexed Tree

ID	Problem	Leetcode ID	Difficulty
1	Find the Longest Valid Obstacle Course at Each Position	1964	Hard

Binary Search

ID	Problem	Leetcode ID	Difficulty
1	Sell Diminishing-Valued Colored Balls	1648	Medium
2	Building Boxes	1739	Hard
3	Minimum Absolute Sum Difference	1818	Medium
4	Frequency of the Most Frequent Element	1838	Medium
5	Minimum Interval to Include Each Query	1851	Hard
6	Maximum Distance Between a Pair of Values	1855	Medium
7	Minimum Speed to Arrive on Time	1870	Medium
8	Minimum Space Wasted From Packaging	1889	Hard
9	Maximum Number of Removable Characters	1898	Medium
10	Find K Closest Elements	658	Medium
11	Max Sum of Rectangle No Larger Than K	363	Hard
12	Kth Smallest Element in a Sorted Matrix	378	Medium
13	Maximum Length of Repeated Subarray	718	Medium
14	Longest Increasing Subsequence	300	Medium
15	Merge BSTs to Create Single BST	1932	Hard
16	Find Peak Element	162	Medium
17	Valid Triangle Number	611	Medium
18	Minimum Garden Perimeter to Collect Enough Apples	1954	Medium
19	Find the Longest Valid Obstacle Course at Each Position	1964	Hard
20	Last Day Where You Can Still Cross	1970	Hard
21	Intersection of Two Arrays II	350	Easy
22	Intersection of Two Arrays	349	Easy
23	Sum of Square Numbers	633	Medium
24	Maximum Profit in Job Scheduling	1235	Hard
25	Find Minimum in Rotated Sorted Array	153	Medium
26	First Bad Version	278	Easy
27	Maximum Earnings From Taxi	2008	Medium
28	Minimum Number of Operations to Make Array Continuous	2009	Hard
29	Find First and Last Position of Element in Sorted Array	34	Medium
30	Search in Rotated Sorted Array	33	Medium
31	Maximize the Confusion of an Exam	2024	Medium
32	Max Consecutive Ones III	1004	Medium
33	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard
34	Search a 2D Matrix II	240	Medium
35	Guess Number Higher or Lower	374	Easy
36	Sqrt(x)	69	Easy
37	Find Minimum in Rotated Sorted Array II	154	Hard
38	Count Complete Tree Nodes	222	Medium
39	Path With Minimum Effort	1631	Medium
40	Arranging Coins	441	Easy
41	Two Best Non-Overlapping Events	2054	Medium
42	Plates Between Candles	2055	Medium
43	Minimized Maximum of Products Distributed to Any Store	2064	Medium
44	Most Beautiful Item for Each Query	2070	Medium
45	Kth Smallest Number in Multiplication Table	668	Hard
46	Single Element in a Sorted Array	540	Medium
47	Range Frequency Queries	2080	Medium

Binary Search Tree

ID	Problem	Leetcode ID	Difficulty
1	Two Sum IV - Input is a BST	653	Easy
2	Validate Binary Search Tree	98	Medium
3	Convert Sorted Array to Binary Search Tree	108	Easy
4	Unique Binary Search Trees II	95	Medium
5	Kth Smallest Element in a BST	230	Medium
6	Construct Binary Search Tree from Preorder Traversal	1008	Medium
7	Unique Binary Search Trees	96	Medium
8	Delete Node in a BST	450	Medium

Binary Tree

ID	Problem	Leetcode ID	Difficulty
1	Merge BSTs to Create Single BST	1932	Hard
2	Binary Tree Pruning	814	Medium
3	Path Sum II	113	Medium
4	Count Good Nodes in Binary Tree	1448	Medium
5	Maximum Product of Splitted Binary Tree	1339	Medium
6	Two Sum IV - Input is a BST	653	Easy
7	Verify Preorder Serialization of a Binary Tree	331	Medium
8	Maximum Depth of Binary Tree	104	Easy
9	Validate Binary Search Tree	98	Medium
10	Symmetric Tree	101	Easy
11	Binary Tree Level Order Traversal	102	Medium
12	Convert Sorted Array to Binary Search Tree	108	Easy
13	Unique Binary Search Trees II	95	Medium
14	Binary Tree Zigzag Level Order Traversal	103	Medium
15	Construct Binary Tree from Preorder and Inorder Traversal	105	Medium
16	Kth Smallest Element in a BST	230	Medium
17	Binary Tree Inorder Traversal	94	Easy
18	Subtree of Another Tree	572	Easy
19	Diameter of Binary Tree	543	Easy
20	Construct Binary Search Tree from Preorder Traversal	1008	Medium
21	Path Sum III	437	Medium
22	Cousins in Binary Tree	993	Easy
23	Count Complete Tree Nodes	222	Medium
24	Invert Binary Tree	226	Easy
25	Sum Root to Leaf Numbers	129	Medium
26	Sum of Left Leaves	404	Easy
27	Unique Binary Search Trees	96	Medium
28	Delete Nodes And Return Forest	1110	Medium
29	Find Leaves of Binary Tree	366	Medium
30	Construct Binary Tree from Inorder and Postorder Traversal	106	Medium
31	Delete Node in a BST	450	Medium

Bit Manipulation

ID	Problem	Leetcode ID	Difficulty
1	Decode XORed Array	1720	Easy
2	Find Minimum Time to Finish All Jobs	1723	Hard
3	Find Kth Largest XOR Coordinate Value	1738	Medium
4	Find XOR Sum of All Pairs Bitwise AND	1835	Hard
5	Sum of All Subset XOR Totals	1863	Easy
6	Number of Wonderful Substrings	1915	Medium
7	Gray Code	89	Medium
8	Maximum Compatibility Score Sum	1947	Medium
9	Subsets II	90	Medium
10	Subsets	78	Medium
11	Single Number	136	Easy
12	Minimum Number of Work Sessions to Finish the Tasks	1986	Medium
13	Number of 1 Bits	191	Easy
14	Hamming Distance	461	Easy
15	Reverse Bits	190	Easy
16	Missing Number	268	Easy
17	Maximum Length of a Concatenated String with Unique Characters	1239	Medium
18	Partition to K Equal Sum Subsets	698	Medium
19	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard
20	Bitwise AND of Numbers Range	201	Medium
21	Count Number of Maximum Bitwise-OR Subsets	2044	Medium
22	Sum of Two Integers	371	Medium
23	Single Number III	260	Medium
24	Number of Valid Words for Each Puzzle	1178	Hard

Bitmask

ID	Problem	Leetcode ID	Difficulty
1	Find Minimum Time to Finish All Jobs	1723	Hard
2	Maximum Compatibility Score Sum	1947	Medium
3	Minimum Number of Work Sessions to Finish the Tasks	1986	Medium
4	Partition to K Equal Sum Subsets	698	Medium
5	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard

Breadth-First Search

ID	Problem	Leetcode ID	Difficulty
1	Count Sub Islands	1905	Medium
2	Nearest Exit from Entrance in Maze	1926	Medium
3	01 Matrix	542	Medium
4	Making A Large Island	827	Hard
5	Word Ladder II	126	Hard
6	Last Day Where You Can Still Cross	1970	Hard
7	Count Good Nodes in Binary Tree	1448	Medium
8	Two Sum IV - Input is a BST	653	Easy
9	Maximum Depth of Binary Tree	104	Easy
10	Symmetric Tree	101	Easy
11	Binary Tree Level Order Traversal	102	Medium
12	Find All Groups of Farmland	1992	Medium
13	Operations on Tree	1993	Medium
14	Binary Tree Zigzag Level Order Traversal	103	Medium
15	Number of Islands	200	Medium
16	Shortest Path in a Grid with Obstacles Elimination	1293	Hard
17	Island Perimeter	463	Easy
18	Coin Change	322	Medium
19	Perfect Squares	279	Medium
20	The Time When the Network Becomes Idle	2039	Medium
21	Second Minimum Time to Reach Destination	2045	Hard
22	Cousins in Binary Tree	993	Easy
23	Invert Binary Tree	226	Easy
24	Network Delay Time	743	Medium
25	Path With Minimum Effort	1631	Medium
26	Rotting Oranges	994	Medium
27	Minimum Operations to Convert Number	2059	Medium
28	Surrounded Regions	130	Medium
29	Sum of Left Leaves	404	Easy
30	Redundant Connection	684	Medium

Bucket Sort

ID	Problem	Leetcode ID	Difficulty
1	Top K Frequent Elements	347	Medium
2	Sort Characters By Frequency	451	Medium

Combinatorics

ID	Problem	Leetcode ID	Difficulty
1	Number of Ways to Rearrange Sticks With K Sticks Visible	1866	Hard
2	Count Ways to Build Rooms in an Ant Colony	1916	Hard
3	Unique Paths	62	Medium
4	Vowels of All Substrings	2063	Medium

Counting

ID	Problem	Leetcode ID	Difficulty
1	Determine if String Halves Are Alike	1704	Easy
2	Change Minimum Characters to Satisfy One of Three Conditions	1737	Medium
3	Maximum Number of Balls in a Box	1742	Easy
4	Check if One String Swap Can Make Strings Equal	1790	Easy
5	Number of Different Subsequences GCDs	1819	Hard
6	Largest Color Value in a Directed Graph	1857	Hard
7	Maximum Population Year	1854	Easy
8	Redistribute Characters to Make All Strings Equal	1897	Easy
9	Check if All Characters Have Equal Number of Occurrences	1941	Easy
10	First Unique Character in a String	387	Easy
11	Maximum Number of Balloons	1189	Easy
12	Detect Squares	2013	Medium
13	Top K Frequent Elements	347	Medium
14	Longest Subsequence Repeated k Times	2014	Hard
15	Maximum Number of Ways to Partition an Array	2025	Hard
16	Majority Element	169	Easy
17	Sort Characters By Frequency	451	Medium
18	Task Scheduler	621	Medium
19	Kth Distinct String in an Array	2053	Easy
20	Check Whether Two Strings are Almost Equivalent	2068	Easy

Data Stream

ID	Problem	Leetcode ID	Difficulty
1	Design an Ordered Stream	1656	Easy

Depth-First Search

ID	Problem	Leetcode ID	Difficulty
1	Where Will the Ball Fall	1706	Medium
2	Minimize Hamming Distance After Swap Operations	1722	Medium
3	Count Sub Islands	1905	Medium
4	Merge BSTs to Create Single BST	1932	Hard
5	Binary Tree Pruning	814	Medium
6	Making A Large Island	827	Hard
7	Path Sum II	113	Medium
8	Last Day Where You Can Still Cross	1970	Hard
9	Count Good Nodes in Binary Tree	1448	Medium
10	Maximum Product of Splitted Binary Tree	1339	Medium
11	Two Sum IV - Input is a BST	653	Easy
12	Maximum Depth of Binary Tree	104	Easy
13	Validate Binary Search Tree	98	Medium
14	Symmetric Tree	101	Easy
15	Array Nesting	565	Medium
16	Sum of Distances in Tree	834	Hard
17	Find All Groups of Farmland	1992	Medium
18	Kth Smallest Element in a BST	230	Medium
19	Binary Tree Inorder Traversal	94	Easy
20	Number of Islands	200	Medium
21	Subtree of Another Tree	572	Easy
22	Island Perimeter	463	Easy
23	Diameter of Binary Tree	543	Easy
24	Path Sum III	437	Medium
25	Cousins in Binary Tree	993	Easy
26	Count Complete Tree Nodes	222	Medium
27	Invert Binary Tree	226	Easy
28	Network Delay Time	743	Medium
29	Path With Minimum Effort	1631	Medium
30	Surrounded Regions	130	Medium
31	Sum Root to Leaf Numbers	129	Medium
32	Sum of Left Leaves	404	Easy
33	Redundant Connection	684	Medium
34	Delete Nodes And Return Forest	1110	Medium
35	Find Leaves of Binary Tree	366	Medium
36	Longest Absolute File Path	388	Medium

Design

ID	Problem	Leetcode ID	Difficulty
1	Design an Ordered Stream	1656	Easy
2	Finding MK Average	1825	Hard
3	Finding Pairs With a Certain Sum	1865	Medium
4	Map Sum Pairs	677	Medium
5	Range Sum Query - Immutable	303	Easy
6	Operations on Tree	1993	Medium
7	Min Stack	155	Easy
8	Detect Squares	2013	Medium
9	Implement Trie (Prefix Tree)	208	Medium
10	Stock Price Fluctuation	2034	Medium
11	Simple Bank System	2043	Medium
12	Insert Delete GetRandom O(1)	380	Medium
13	Walking Robot Simulation II	2069	Medium
14	Iterator for Combination	1286	Medium
15	Logger Rate Limiter	359	Easy

Divide and Conquer

ID	Problem	Leetcode ID	Difficulty
1	Find Kth Largest XOR Coordinate Value	1738	Medium
2	Beautiful Array	932	Medium
3	Find the Kth Largest Integer in the Array	1985	Medium
4	Convert Sorted Array to Binary Search Tree	108	Easy
5	Maximum Subarray	53	Easy
6	Reverse Bits	190	Easy
7	Construct Binary Tree from Preorder and Inorder Traversal	105	Medium
8	Top K Frequent Elements	347	Medium
9	Kth Largest Element in an Array	215	Medium
10	Search a 2D Matrix II	240	Medium
11	Majority Element	169	Easy
12	Construct Binary Tree from Inorder and Postorder Traversal	106	Medium

Dynamic Programming

ID	Problem	Leetcode ID	Difficulty
1	Get Maximum in Generated Array	1646	Easy
2	Where Will the Ball Fall	1706	Medium
3	Find Minimum Time to Finish All Jobs	1723	Hard
4	Maximum Score from Performing Multiplication Operations	1770	Medium
5	Maximize Palindrome Length From Subsequences	1771	Hard
6	Minimum Sideway Jumps	1824	Medium
7	Largest Color Value in a Directed Graph	1857	Hard
8	Number of Ways to Rearrange Sticks With K Sticks Visible	1866	Hard
9	Stone Game VIII	1872	Hard
10	Minimum Skips to Arrive at Meeting On Time	1883	Hard
11	Count Ways to Build Rooms in an Ant Colony	1916	Hard
12	Max Sum of Rectangle No Larger Than K	363	Hard
13	Count Vowels Permutation	1220	Hard
14	Maximum Alternating Subsequence Sum	1911	Medium
15	Maximum Length of Repeated Subarray	718	Medium
16	Longest Increasing Subsequence	300	Medium
17	Painting a Grid With Three Different Colors	1931	Hard
18	Maximum Number of Points with Cost	1937	Medium
19	Push Dominoes	838	Medium
20	Maximum Compatibility Score Sum	1947	Medium
21	Non-negative Integers without Consecutive Ones	600	Hard
22	01 Matrix	542	Medium
23	Trapping Rain Water	42	Hard
24	Count Number of Special Subsequences	1955	Hard
25	Stone Game	877	Medium
26	Palindrome Partitioning II	132	Hard
27	Flip String to Monotone Increasing	926	Medium
28	Remove Boxes	546	Hard
29	Minimum Total Space Wasted With K Resizing Operations	1959	Medium
30	Decode Ways	91	Medium
31	Best Time to Buy and Sell Stock II	122	Medium
32	Minimize the Difference Between Target and Chosen Elements	1981	Medium
33	Maximum Profit in Job Scheduling	1235	Hard
34	Minimum Number of Work Sessions to Finish the Tasks	1986	Medium
35	Unique Binary Search Trees II	95	Medium
36	Sum of Distances in Tree	834	Hard
37	Climbing Stairs	70	Easy
38	Best Time to Buy and Sell Stock	121	Easy
39	Maximum Subarray	53	Easy
40	House Robber	198	Medium
41	Largest Plus Sign	764	Medium
42	Pascal's Triangle	118	Easy
43	Arithmetic Slices II - Subsequence	446	Hard
44	First Day Where You Have Been in All the Rooms	1997	Medium
45	Number of Unique Good Subsequences	1987	Hard
46	Longest Turbulent Subarray	978	Medium
47	Maximum Earnings From Taxi	2008	Medium
48	Distinct Subsequences	115	Hard
49	Longest Palindromic Substring	5	Medium
50	Generate Parentheses	22	Medium
51	N-th Tribonacci Number	1137	Easy
52	Partition to K Equal Sum Subsets	698	Medium
53	Longest Common Subsequence	1143	Medium
54	Jump Game	55	Medium
55	Dungeon Game	174	Hard
56	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard
57	Unique Paths	62	Medium
58	Coin Change	322	Medium
59	Perfect Squares	279	Medium
60	Best Time to Buy and Sell Stock with Cooldown	309	Medium
61	Best Time to Buy and Sell Stock III	123	Hard
62	Two Best Non-Overlapping Events	2054	Medium
63	Vowels of All Substrings	2063	Medium
64	Unique Binary Search Trees	96	Medium
65	Largest Divisible Subset	368	Medium

Enumeration

ID	Problem	Leetcode ID	Difficulty
1	Count Square Sum Triples	1925	Easy
2	Check if Move is Legal	1958	Medium
3	Count Primes	204	Easy
4	Count Special Quadruplets	1995	Easy
5	Check if Word Can Be Placed In Crossword	2018	Medium
6	Longest Subsequence Repeated k Times	2014	Hard
7	Maximum Number of Ways to Partition an Array	2025	Hard

Game Theory

ID	Problem	Leetcode ID	Difficulty
1	Stone Game VIII	1872	Hard
2	Sum Game	1927	Medium
3	Stone Game	877	Medium
4	Remove Colored Pieces if Both Neighbors are the Same Color	2038	Medium
5	Guess the Word	843	Hard

Graph

ID	Problem	Leetcode ID	Difficulty
1	Minimum Degree of a Connected Trio in a Graph	1761	Hard
2	Find Center of Star Graph	1791	Easy
3	Largest Color Value in a Directed Graph	1857	Hard
4	Count Ways to Build Rooms in an Ant Colony	1916	Hard
5	Sum of Distances in Tree	834	Hard
6	The Time When the Network Becomes Idle	2039	Medium
7	Second Minimum Time to Reach Destination	2045	Hard
8	Network Delay Time	743	Medium
9	Path with Maximum Probability	1514	Medium
10	Maximum Path Quality of a Graph	2065	Hard
11	Process Restricted Friend Requests	2076	Hard
12	Redundant Connection	684	Medium

Greedy

ID	Problem	Leetcode ID	Difficulty
1	Minimum Deletions to Make Character Frequencies Unique	1647	Medium
2	Sell Diminishing-Valued Colored Balls	1648	Medium
3	Smallest String With A Given Numeric Value	1663	Medium
4	Find the Most Competitive Subsequence	1673	Medium
5	Partitioning Into Minimum Number Of Deci-Binary Numbers	1689	Medium
6	Maximum Number of Eaten Apples	1705	Medium
7	Maximum Units on a Truck	1710	Easy
8	Largest Submatrix With Rearrangements	1727	Medium
9	Latest Time by Replacing Hidden Digits	1736	Easy
10	Building Boxes	1739	Hard
11	Maximum Average Pass Ratio	1792	Medium
12	Minimum Sideway Jumps	1824	Medium
13	Maximum Ice Cream Bars	1833	Medium
14	Frequency of the Most Frequent Element	1838	Medium
15	Minimum Number of Swaps to Make the Binary String Alternating	1864	Medium
16	Minimum Adjacent Swaps to Reach the Kth Smallest Number	1850	Medium
17	Maximum Distance Between a Pair of Values	1855	Medium
18	Merge Triplets to Form Target Triplet	1899	Medium
19	Maximum Value after Insertion	1881	Medium
20	Largest Odd Number in String	1903	Easy
21	Minimum Number of Flips to Make the Binary String Alternating	1888	Medium
22	Eliminate Maximum Number of Monsters	1921	Medium
23	Reduce Array Size to The Half	1338	Medium
24	Valid Triangle Number	611	Medium
25	Sum Game	1927	Medium
26	Add Minimum Number of Rungs	1936	Medium
27	Maximum Number of Weeks for Which You Can Work	1953	Medium
28	Minimum Number of Swaps to Make the String Balanced	1963	Medium
29	Largest Number After Mutating Substring	1946	Medium
30	Array of Doubled Pairs	954	Medium
31	Array With Elements Not Equal to Average of Neighbors	1968	Medium
32	Minimum Non-Zero Product of the Array Elements	1969	Medium
33	Best Time to Buy and Sell Stock II	122	Medium
34	Minimum Time to Type Word Using Special Typewriter	1974	Easy
35	Maximum Matrix Sum	1975	Medium
36	Patching Array	330	Hard
37	The Number of Weak Characters in the Game	1996	Medium
38	Find Original Array From Doubled Array	2007	Medium
39	Increasing Triplet Subsequence	334	Medium
40	Break a Palindrome	1328	Medium
41	Jump Game	55	Medium
42	Longest Subsequence Repeated k Times	2014	Hard
43	Remove Colored Pieces if Both Neighbors are the Same Color	2038	Medium
44	Task Scheduler	621	Medium

Hash Function

ID	Problem	Leetcode ID	Difficulty
1	Maximum Length of Repeated Subarray	718	Medium
2	Subtree of Another Tree	572	Easy

Hash Table

ID	Problem	Leetcode ID	Difficulty
1	Design an Ordered Stream	1656	Easy
2	Determine if Two Strings Are Close	1657	Medium
3	Minimum Moves to Make Array Complementary	1674	Medium
4	Count Good Meals	1711	Medium
5	Tuple with Same Product	1726	Medium
6	Change Minimum Characters to Satisfy One of Three Conditions	1737	Medium
7	Maximum Number of Balls in a Box	1742	Easy
8	Restore the Array From Adjacent Pairs	1743	Medium
9	Check if One String Swap Can Make Strings Equal	1790	Easy
10	Number of Different Integers in a String	1805	Easy
11	Finding the Users Active Minutes	1817	Medium
12	Check if the Sentence Is Pangram	1832	Easy
13	Finding Pairs With a Certain Sum	1865	Medium
14	Largest Color Value in a Directed Graph	1857	Hard
15	Redistribute Characters to Make All Strings Equal	1897	Easy
16	Minimum Absolute Difference Queries	1906	Medium
17	Number of Wonderful Substrings	1915	Medium
18	Reduce Array Size to The Half	1338	Medium
19	Merge BSTs to Create Single BST	1932	Hard
20	Unique Length-3 Palindromic Subsequences	1930	Medium
21	Isomorphic Strings	205	Easy
22	Custom Sort String	791	Medium
23	Maximum Number of Words You Can Type	1935	Easy
24	Map Sum Pairs	677	Medium
25	Check if All Characters Have Equal Number of Occurrences	1941	Easy
26	Array of Doubled Pairs	954	Medium
27	Group Anagrams	49	Medium
28	Set Matrix Zeroes	73	Medium
29	Word Ladder II	126	Hard
30	Minimum Window Substring	76	Hard
31	Contains Duplicate	217	Easy
32	Intersection of Two Arrays II	350	Easy
33	Intersection of Two Arrays	349	Easy
34	Two Sum	1	Easy
35	Valid Sudoku	36	Medium
36	First Unique Character in a String	387	Easy
37	Valid Anagram	242	Easy
38	Two Sum IV - Input is a BST	653	Easy
39	Longest Uncommon Subsequence II	522	Medium
40	Linked List Cycle	141	Easy
41	Operations on Tree	1993	Medium
42	Roman to Integer	13	Easy
43	Missing Number	268	Easy
44	Maximum Number of Balloons	1189	Easy
45	Find Original Array From Doubled Array	2007	Medium
46	Detect Squares	2013	Medium
47	Find Winner on a Tic Tac Toe Game	1275	Easy
48	Longest Substring Without Repeating Characters	3	Medium
49	Intersection of Two Linked Lists	160	Easy
50	Construct Binary Tree from Preorder and Inorder Traversal	105	Medium
51	Letter Combinations of a Phone Number	17	Medium
52	Top K Frequent Elements	347	Medium
53	Unique Email Addresses	929	Easy
54	Find All Duplicates in an Array	442	Medium
55	Implement Trie (Prefix Tree)	208	Medium
56	Longest Repeating Character Replacement	424	Medium
57	Maximum Number of Ways to Partition an Array	2025	Hard
58	Two Out of Three	2032	Easy
59	Stock Price Fluctuation	2034	Medium
60	Simple Bank System	2043	Medium
61	Happy Number	202	Easy
62	Next Greater Element I	496	Easy
63	Insert Delete GetRandom O(1)	380	Medium
64	Majority Element	169	Easy
65	Sort Characters By Frequency	451	Medium
66	Task Scheduler	621	Medium
67	Kth Distinct String in an Array	2053	Easy
68	Number of Valid Words for Each Puzzle	1178	Hard
69	First Missing Positive	41	Hard
70	Check Whether Two Strings are Almost Equivalent	2068	Easy
71	Find All Numbers Disappeared in an Array	448	Easy
72	Logger Rate Limiter	359	Easy
73	Construct Binary Tree from Inorder and Postorder Traversal	106	Medium
74	Count Vowel Substrings of a String	2062	Easy

Heap (Priority Queue)

ID	Problem	Leetcode ID	Difficulty
1	Sell Diminishing-Valued Colored Balls	1648	Medium
2	Maximum Number of Eaten Apples	1705	Medium
3	Find Kth Largest XOR Coordinate Value	1738	Medium
4	Maximum Average Pass Ratio	1792	Medium
5	Number of Orders in the Backlog	1801	Medium
6	Finding MK Average	1825	Hard
7	Single-Threaded CPU	1834	Medium
8	Minimum Interval to Include Each Query	1851	Hard
9	Process Tasks Using Servers	1882	Medium
10	Find K Closest Elements	658	Medium
11	Reduce Array Size to The Half	1338	Medium
12	Kth Smallest Element in a Sorted Matrix	378	Medium
13	The Number of the Smallest Unoccupied Chair	1942	Medium
14	Remove Stones to Minimize the Total	1962	Medium
15	Find the Kth Largest Integer in the Array	1985	Medium
16	Top K Frequent Elements	347	Medium
17	Kth Largest Element in an Array	215	Medium
18	Stock Price Fluctuation	2034	Medium
19	Sort Characters By Frequency	451	Medium
20	Task Scheduler	621	Medium
21	Network Delay Time	743	Medium
22	Path with Maximum Probability	1514	Medium
23	Path With Minimum Effort	1631	Medium
24	Two Best Non-Overlapping Events	2054	Medium
25	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Medium

Interactive

ID	Problem	Leetcode ID	Difficulty
1	First Bad Version	278	Easy
2	Guess Number Higher or Lower	374	Easy
3	Guess the Word	843	Hard

Iterator

ID	Problem	Leetcode ID	Difficulty
1	Iterator for Combination	1286	Medium

Line Sweep

ID	Problem	Leetcode ID	Difficulty
1	Minimum Interval to Include Each Query	1851	Hard
2	Rectangle Area II	850	Hard

Linked List

ID	Problem	Leetcode ID	Difficulty
1	Swapping Nodes in a Linked List	1721	Medium
2	Delete Node in a Linked List	237	Easy
3	Remove Nth Node From End of List	19	Medium
4	Merge Two Sorted Lists	21	Easy
5	Palindrome Linked List	234	Easy
6	Linked List Cycle	141	Easy
7	Reverse Linked List	206	Easy
8	Add Two Numbers	2	Medium
9	Odd Even Linked List	328	Medium
10	Intersection of Two Linked Lists	160	Easy
11	Split Linked List in Parts	725	Medium
12	Find the Minimum and Maximum Number of Nodes Between Critical Points	2058	Medium
13	Remove Linked List Elements	203	Easy
14	Reverse Nodes in Even Length Groups	2074	Medium

Math

ID	Problem	Leetcode ID	Difficulty
1	Sell Diminishing-Valued Colored Balls	1648	Medium
2	Count of Matches in Tournament	1688	Easy
3	Building Boxes	1739	Hard
4	Maximum Number of Balls in a Box	1742	Easy
5	Count Number of Homogenous Substrings	1759	Medium
6	Number of Different Subsequences GCDs	1819	Hard
7	Sign of the Product of an Array	1822	Easy
8	Find the Winner of the Circular Game	1823	Medium
9	Find XOR Sum of All Pairs Bitwise AND	1835	Hard
10	Sum of Digits in Base K	1837	Easy
11	Maximum Building Height	1840	Hard
12	Number of Ways to Rearrange Sticks With K Sticks Visible	1866	Hard
13	Stone Game VIII	1872	Hard
14	Largest Odd Number in String	1903	Easy
15	Count Ways to Build Rooms in an Ant Colony	1916	Hard
16	Count Good Numbers	1922	Medium
17	Gray Code	89	Medium
18	The Number of Full Rounds You Have Played	1904	Medium
19	Count Square Sum Triples	1925	Easy
20	Sum Game	1927	Medium
21	Three Equal Parts	927	Hard
22	Beautiful Array	932	Medium
23	Three Divisors	1952	Easy
24	Minimum Garden Perimeter to Collect Enough Apples	1954	Medium
25	Stone Game	877	Medium
26	Add Strings	415	Easy
27	Minimum Non-Zero Product of the Array Elements	1969	Medium
28	Rotate Array	189	Medium
29	Plus One	66	Easy
30	Rotate Image	48	Medium
31	Reverse Integer	7	Easy
32	Find Greatest Common Divisor of Array	1979	Easy
33	Complex Number Multiplication	537	Medium
34	Sum of Square Numbers	633	Medium
35	Range Addition II	598	Easy
36	Climbing Stairs	70	Easy
37	Shuffle an Array	384	Medium
38	Orderly Queue	899	Hard
39	Fizz Buzz	412	Easy
40	Count Primes	204	Easy
41	Power of Three	326	Easy
42	Roman to Integer	13	Easy
43	Missing Number	268	Easy
44	Basic Calculator	224	Hard
45	Expression Add Operators	282	Hard
46	Add Two Numbers	2	Medium
47	GCD Sort of an Array	1998	Hard
48	N-th Tribonacci Number	1137	Easy
49	Minimum Operations to Make a Uni-Value Grid	2033	Medium
50	Unique Paths	62	Medium
51	Perfect Squares	279	Medium
52	Remove Colored Pieces if Both Neighbors are the Same Color	2038	Medium
53	Happy Number	202	Easy
54	Factorial Trailing Zeroes	172	Medium
55	Excel Sheet Column Number	171	Easy
56	Pow(x, n)	50	Medium
57	Sqrt(x)	69	Easy
58	Sum of Two Integers	371	Medium
59	Insert Delete GetRandom O(1)	380	Medium
60	Evaluate Reverse Polish Notation	150	Medium
61	Arranging Coins	441	Easy
62	Vowels of All Substrings	2063	Medium
63	Multiply Strings	43	Medium
64	Unique Binary Search Trees	96	Medium
65	Guess the Word	843	Hard
66	Largest Divisible Subset	368	Medium

Matrix

ID	Problem	Leetcode ID	Difficulty
1	Richest Customer Wealth	1672	Easy
2	Where Will the Ball Fall	1706	Medium
3	Largest Submatrix With Rearrangements	1727	Medium
4	Find Kth Largest XOR Coordinate Value	1738	Medium
5	Determine Whether Matrix Can Be Obtained By Rotation	1886	Easy
6	Count Sub Islands	1905	Medium
7	Cyclically Rotating a Grid	1914	Medium
8	Max Sum of Rectangle No Larger Than K	363	Hard
9	Reshape the Matrix	566	Easy
10	Kth Smallest Element in a Sorted Matrix	378	Medium
11	Nearest Exit from Entrance in Maze	1926	Medium
12	01 Matrix	542	Medium
13	Making A Large Island	827	Hard
14	Set Matrix Zeroes	73	Medium
15	Last Day Where You Can Still Cross	1970	Hard
16	Check if Move is Legal	1958	Medium
17	Rotate Image	48	Medium
18	Valid Sudoku	36	Medium
19	Maximum Matrix Sum	1975	Medium
20	Minimize the Difference Between Target and Chosen Elements	1981	Medium
21	Sudoku Solver	37	Hard
22	Find All Groups of Farmland	1992	Medium
23	Spiral Matrix	54	Medium
24	Find Winner on a Tic Tac Toe Game	1275	Easy
25	Number of Islands	200	Medium
26	Word Search	79	Medium
27	Shortest Path in a Grid with Obstacles Elimination	1293	Hard
28	Grid Game	2017	Medium
29	Check if Word Can Be Placed In Crossword	2018	Medium
30	Dungeon Game	174	Hard
31	Island Perimeter	463	Easy
32	Convert 1D Array Into 2D Array	2022	Easy
33	Word Search II	212	Hard
34	Minimum Operations to Make a Uni-Value Grid	2033	Medium
35	Search a 2D Matrix II	240	Medium
36	Path With Minimum Effort	1631	Medium
37	Rotting Oranges	994	Medium
38	Surrounded Regions	130	Medium

Memoization

ID	Problem	Leetcode ID	Difficulty
1	Largest Color Value in a Directed Graph	1857	Hard
2	Remove Boxes	546	Hard
3	Climbing Stairs	70	Easy
4	N-th Tribonacci Number	1137	Easy
5	Partition to K Equal Sum Subsets	698	Medium

Monotonic Queue

ID	Problem	Leetcode ID	Difficulty
1	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Medium

Monotonic Stack

ID	Problem	Leetcode ID	Difficulty
1	Find the Most Competitive Subsequence	1673	Medium
2	Maximum Subarray Min-Product	1856	Medium
3	Number of Visible People in a Queue	1944	Hard
4	Trapping Rain Water	42	Hard
5	The Number of Weak Characters in the Game	1996	Medium
6	Construct Binary Search Tree from Preorder Traversal	1008	Medium
7	Next Greater Element I	496	Easy
8	Daily Temperatures	739	Medium

Number Theory

ID	Problem	Leetcode ID	Difficulty
1	Number of Different Subsequences GCDs	1819	Hard
2	Count Primes	204	Easy

Ordered Set

ID	Problem	Leetcode ID	Difficulty
1	Minimum Absolute Sum Difference	1818	Medium
2	Finding MK Average	1825	Hard
3	Max Sum of Rectangle No Larger Than K	363	Hard
4	The Number of the Smallest Unoccupied Chair	1942	Medium
5	Rectangle Area II	850	Hard
6	Stock Price Fluctuation	2034	Medium
7	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard
8	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Medium

Prefix Sum

ID	Problem	Leetcode ID	Difficulty
1	Minimum Moves to Make Array Complementary	1674	Medium
2	Change Minimum Characters to Satisfy One of Three Conditions	1737	Medium
3	Find Kth Largest XOR Coordinate Value	1738	Medium
4	Frequency of the Most Frequent Element	1838	Medium
5	Maximum Subarray Min-Product	1856	Medium
6	Jump Game VII	1871	Medium
7	Stone Game VIII	1872	Hard
8	Minimum Space Wasted From Packaging	1889	Hard
9	Number of Wonderful Substrings	1915	Medium
10	Unique Length-3 Palindromic Subsequences	1930	Medium
11	Describe the Painting	1943	Medium
12	Range Sum Query - Immutable	303	Easy
13	Find the Middle Index in Array	1991	Easy
14	Grid Game	2017	Medium
15	Maximize the Confusion of an Exam	2024	Medium
16	Max Consecutive Ones III	1004	Medium
17	Maximum Number of Ways to Partition an Array	2025	Hard
18	Plates Between Candles	2055	Medium
19	Minimum Value to Get Positive Step by Step Sum	1413	Easy

Queue

ID	Problem	Leetcode ID	Difficulty
1	Find the Winner of the Circular Game	1823	Medium
2	Finding MK Average	1825	Hard
3	First Unique Character in a String	387	Easy
4	Time Needed to Buy Tickets	2073	Easy
5	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Medium

Quickselect

ID	Problem	Leetcode ID	Difficulty
1	Find Kth Largest XOR Coordinate Value	1738	Medium
2	Find the Kth Largest Integer in the Array	1985	Medium
3	Top K Frequent Elements	347	Medium
4	Kth Largest Element in an Array	215	Medium

Randomized

ID	Problem	Leetcode ID	Difficulty
1	Shuffle an Array	384	Medium
2	Insert Delete GetRandom O(1)	380	Medium

Recursion

ID	Problem	Leetcode ID	Difficulty
1	Find the Winner of the Circular Game	1823	Medium
2	Count Good Numbers	1922	Medium
3	Minimum Non-Zero Product of the Array Elements	1969	Medium
4	Reverse String	344	Easy
5	Merge Two Sorted Lists	21	Easy
6	Palindrome Linked List	234	Easy
7	Reverse Linked List	206	Easy
8	Power of Three	326	Easy
9	Basic Calculator	224	Hard
10	Add Two Numbers	2	Medium
11	Pow(x, n)	50	Medium
12	Remove Linked List Elements	203	Easy
13	Decode String	394	Medium

Rolling Hash

ID	Problem	Leetcode ID	Difficulty
1	Maximum Length of Repeated Subarray	718	Medium

Segment Tree

ID	Problem	Leetcode ID	Difficulty
1	Rectangle Area II	850	Hard

Shortest Path

ID	Problem	Leetcode ID	Difficulty
1	Second Minimum Time to Reach Destination	2045	Hard
2	Network Delay Time	743	Medium
3	Path with Maximum Probability	1514	Medium

Simulation

ID	Problem	Leetcode ID	Difficulty
1	Get Maximum in Generated Array	1646	Easy
2	Count of Matches in Tournament	1688	Easy
3	Where Will the Ball Fall	1706	Medium
4	Number of Orders in the Backlog	1801	Medium
5	Find the Winner of the Circular Game	1823	Medium
6	Cyclically Rotating a Grid	1914	Medium
7	Build Array from Permutation	1920	Easy
8	Reshape the Matrix	566	Easy
9	Sum of Digits of String After Convert	1945	Easy
10	Add Strings	415	Easy
11	Complex Number Multiplication	537	Medium
12	Fizz Buzz	412	Easy
13	Spiral Matrix	54	Medium
14	Final Value of Variable After Performing Operations	2011	Easy
15	Find Winner on a Tic Tac Toe Game	1275	Easy
16	Convert 1D Array Into 2D Array	2022	Easy
17	Simple Bank System	2043	Medium
18	Multiply Strings	43	Medium
19	Walking Robot Simulation II	2069	Medium
20	Time Needed to Buy Tickets	2073	Easy
21	Decode the Slanted Ciphertext	2075	Medium
22	Validate Stack Sequences	946	Medium
23	Text Justification	68	Hard

Sliding Window

ID	Problem	Leetcode ID	Difficulty
1	Frequency of the Most Frequent Element	1838	Medium
2	Longest Substring Of All Vowels in Order	1839	Medium
3	Maximum Length of Repeated Subarray	718	Medium
4	Minimum Window Substring	76	Hard
5	Longest Turbulent Subarray	978	Medium
6	Longest Substring Without Repeating Characters	3	Medium
7	Maximize the Confusion of an Exam	2024	Medium
8	Max Consecutive Ones III	1004	Medium
9	Longest Repeating Character Replacement	424	Medium
10	Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit	1438	Medium

Sorting

ID	Problem	Leetcode ID	Difficulty
1	Minimum Deletions to Make Character Frequencies Unique	1647	Medium
2	Sell Diminishing-Valued Colored Balls	1648	Medium
3	Determine if Two Strings Are Close	1657	Medium
4	Maximum Units on a Truck	1710	Easy
5	Largest Submatrix With Rearrangements	1727	Medium
6	Minimum Absolute Sum Difference	1818	Medium
7	Maximum Ice Cream Bars	1833	Medium
8	Single-Threaded CPU	1834	Medium
9	Frequency of the Most Frequent Element	1838	Medium
10	Minimum Interval to Include Each Query	1851	Hard
11	Reduction Operations to Make the Array Elements Equal	1887	Medium
12	Minimum Space Wasted From Packaging	1889	Hard
13	Maximum Product Difference Between Two Pairs	1913	Easy
14	Find K Closest Elements	658	Medium
15	Eliminate Maximum Number of Monsters	1921	Medium
16	Reduce Array Size to The Half	1338	Medium
17	Kth Smallest Element in a Sorted Matrix	378	Medium
18	Custom Sort String	791	Medium
19	Valid Triangle Number	611	Medium
20	3Sum Closest	16	Medium
21	Array of Doubled Pairs	954	Medium
22	Group Anagrams	49	Medium
23	Array With Elements Not Equal to Average of Neighbors	1968	Medium
24	Contains Duplicate	217	Easy
25	Intersection of Two Arrays II	350	Easy
26	Intersection of Two Arrays	349	Easy
27	Valid Anagram	242	Easy
28	Merge Intervals	56	Medium
29	Longest Uncommon Subsequence II	522	Medium
30	Minimum Difference Between Highest and Lowest of K Scores	1984	Easy
31	Find the Kth Largest Integer in the Array	1985	Medium
32	Maximum Profit in Job Scheduling	1235	Hard
33	Merge Sorted Array	88	Easy
34	Orderly Queue	899	Hard
35	Missing Number	268	Easy
36	The Number of Weak Characters in the Game	1996	Medium
37	Find Original Array From Doubled Array	2007	Medium
38	Maximum Earnings From Taxi	2008	Medium
39	3Sum	15	Medium
40	GCD Sort of an Array	1998	Hard
41	Sort Colors	75	Medium
42	Top K Frequent Elements	347	Medium
43	Sort Array By Parity II	922	Easy
44	Kth Largest Element in an Array	215	Medium
45	Minimum Operations to Make a Uni-Value Grid	2033	Medium
46	Minimum Number of Moves to Seat Everyone	2037	Easy
47	Majority Element	169	Easy
48	Sort Characters By Frequency	451	Medium
49	Task Scheduler	621	Medium
50	Two Best Non-Overlapping Events	2054	Medium
51	Most Beautiful Item for Each Query	2070	Medium
52	Largest Divisible Subset	368	Medium

Stack

ID	Problem	Leetcode ID	Difficulty
1	Find the Most Competitive Subsequence	1673	Medium
2	Maximum Subarray Min-Product	1856	Medium
3	Number of Visible People in a Queue	1944	Hard
4	Trapping Rain Water	42	Hard
5	Minimum Number of Swaps to Make the String Balanced	1963	Medium
6	Verify Preorder Serialization of a Binary Tree	331	Medium
7	Palindrome Linked List	234	Easy
8	Min Stack	155	Easy
9	Valid Parentheses	20	Easy
10	Basic Calculator	224	Hard
11	The Number of Weak Characters in the Game	1996	Medium
12	Binary Tree Inorder Traversal	94	Easy
13	Construct Binary Search Tree from Preorder Traversal	1008	Medium
14	Next Greater Element I	496	Easy
15	Evaluate Reverse Polish Notation	150	Medium
16	Daily Temperatures	739	Medium
17	Validate Stack Sequences	946	Medium
18	Longest Absolute File Path	388	Medium
19	Decode String	394	Medium

String

ID	Problem	Leetcode ID	Difficulty
1	Minimum Deletions to Make Character Frequencies Unique	1647	Medium
2	Determine if Two Strings Are Close	1657	Medium
3	Check If Two String Arrays are Equivalent	1662	Easy
4	Smallest String With A Given Numeric Value	1663	Medium
5	Partitioning Into Minimum Number Of Deci-Binary Numbers	1689	Medium
6	Determine if String Halves Are Alike	1704	Easy
7	Latest Time by Replacing Hidden Digits	1736	Easy
8	Change Minimum Characters to Satisfy One of Three Conditions	1737	Medium
9	Minimum Changes To Make Alternating Binary String	1758	Easy
10	Count Number of Homogenous Substrings	1759	Medium
11	Merge Strings Alternately	1768	Easy
12	Minimum Number of Operations to Move All Balls to Each Box	1769	Medium
13	Maximize Palindrome Length From Subsequences	1771	Hard
14	Check if Binary String Has at Most One Segment of Ones	1784	Easy
15	Check if One String Swap Can Make Strings Equal	1790	Easy
16	Number of Different Integers in a String	1805	Easy
17	Truncate Sentence	1816	Easy
18	Check if the Sentence Is Pangram	1832	Easy
19	Longest Substring Of All Vowels in Order	1839	Medium
20	Minimum Number of Swaps to Make the Binary String Alternating	1864	Medium
21	Splitting a String Into Descending Consecutive Values	1849	Medium
22	Minimum Adjacent Swaps to Reach the Kth Smallest Number	1850	Medium
23	Longer Contiguous Segments of Ones than Zeros	1869	Easy
24	Jump Game VII	1871	Medium
25	Redistribute Characters to Make All Strings Equal	1897	Easy
26	Check if Word Equals Summation of Two Words	1880	Easy
27	Maximum Value after Insertion	1881	Medium
28	Largest Odd Number in String	1903	Easy
29	Minimum Number of Flips to Make the Binary String Alternating	1888	Medium
30	Number of Wonderful Substrings	1915	Medium
31	Maximum Number of Removable Characters	1898	Medium
32	Remove All Occurrences of a Substring	1910	Medium
33	The Number of Full Rounds You Have Played	1904	Medium
34	Unique Length-3 Palindromic Subsequences	1930	Medium
35	Isomorphic Strings	205	Easy
36	Custom Sort String	791	Medium
37	Maximum Number of Words You Can Type	1935	Easy
38	Push Dominoes	838	Medium
39	Sum of Digits of String After Convert	1945	Easy
40	Map Sum Pairs	677	Medium
41	Check if All Characters Have Equal Number of Occurrences	1941	Easy
42	Palindrome Partitioning II	132	Hard
43	Minimum Number of Swaps to Make the String Balanced	1963	Medium
44	Check If String Is a Prefix of Array	1961	Easy
45	Add Strings	415	Easy
46	Largest Number After Mutating Substring	1946	Medium
47	Flip String to Monotone Increasing	926	Medium
48	Group Anagrams	49	Medium
49	Word Ladder II	126	Hard
50	Minimum Window Substring	76	Hard
51	Delete Characters to Make Fancy String	1957	Easy
52	Decode Ways	91	Medium
53	Reverse String	344	Easy
54	First Unique Character in a String	387	Easy
55	Valid Anagram	242	Easy
56	Valid Palindrome	125	Easy
57	String to Integer (atoi)	8	Medium
58	Implement strStr()	28	Easy
59	Minimum Time to Type Word Using Special Typewriter	1974	Easy
60	Find Unique Binary String	1980	Medium
61	Complex Number Multiplication	537	Medium
62	Count and Say	38	Medium
63	Longest Common Prefix	14	Easy
64	Verify Preorder Serialization of a Binary Tree	331	Medium
65	Longest Uncommon Subsequence II	522	Medium
66	Find the Kth Largest Integer in the Array	1985	Medium
67	Number of Strings That Appear as Substrings in Word	1967	Easy
68	Orderly Queue	899	Hard
69	Slowest Key	1629	Easy
70	Fizz Buzz	412	Easy
71	Shifting Letters	848	Medium
72	Roman to Integer	13	Easy
73	Valid Parentheses	20	Easy
74	Basic Calculator	224	Hard
75	Maximum Number of Balloons	1189	Easy
76	Reverse Only Letters	917	Easy
77	Number of Unique Good Subsequences	1987	Hard
78	Expression Add Operators	282	Hard
79	Final Value of Variable After Performing Operations	2011	Easy
80	Distinct Subsequences	115	Hard
81	Longest Substring Without Repeating Characters	3	Medium
82	Longest Palindromic Substring	5	Medium
83	Maximum Length of a Concatenated String with Unique Characters	1239	Medium
84	Letter Combinations of a Phone Number	17	Medium
85	Generate Parentheses	22	Medium
86	Break a Palindrome	1328	Medium
87	Unique Email Addresses	929	Easy
88	Longest Common Subsequence	1143	Medium
89	Longest Subsequence Repeated k Times	2014	Hard
90	Implement Trie (Prefix Tree)	208	Medium
91	Number of Pairs of Strings With Concatenation Equal to Target	2023	Medium
92	Maximize the Confusion of an Exam	2024	Medium
93	Longest Repeating Character Replacement	424	Medium
94	Word Search II	212	Hard
95	Remove Colored Pieces if Both Neighbors are the Same Color	2038	Medium
96	Check if Numbers Are Ascending in a Sentence	2042	Easy
97	Excel Sheet Column Number	171	Easy
98	Reverse Words in a String	151	Medium
99	Sort Characters By Frequency	451	Medium
100	Kth Distinct String in an Array	2053	Easy
101	Plates Between Candles	2055	Medium
102	Vowels of All Substrings	2063	Medium
103	Multiply Strings	43	Medium
104	Number of Valid Words for Each Puzzle	1178	Hard
105	Guess the Word	843	Hard
106	Check Whether Two Strings are Almost Equivalent	2068	Easy
107	Decode the Slanted Ciphertext	2075	Medium
108	Iterator for Combination	1286	Medium
109	Expressive Words	809	Medium
110	Text Justification	68	Hard
111	Longest Absolute File Path	388	Medium
112	Decode String	394	Medium
113	Count Vowel Substrings of a String	2062	Easy

String Matching

ID	Problem	Leetcode ID	Difficulty
1	Implement strStr()	28	Easy
2	Subtree of Another Tree	572	Easy

Topological Sort

ID	Problem	Leetcode ID	Difficulty
1	Largest Color Value in a Directed Graph	1857	Hard
2	Count Ways to Build Rooms in an Ant Colony	1916	Hard

Tree

ID	Problem	Leetcode ID	Difficulty
1	Count Ways to Build Rooms in an Ant Colony	1916	Hard
2	Merge BSTs to Create Single BST	1932	Hard
3	Binary Tree Pruning	814	Medium
4	Path Sum II	113	Medium
5	Count Good Nodes in Binary Tree	1448	Medium
6	Maximum Product of Splitted Binary Tree	1339	Medium
7	Two Sum IV - Input is a BST	653	Easy
8	Verify Preorder Serialization of a Binary Tree	331	Medium
9	Maximum Depth of Binary Tree	104	Easy
10	Validate Binary Search Tree	98	Medium
11	Symmetric Tree	101	Easy
12	Binary Tree Level Order Traversal	102	Medium
13	Convert Sorted Array to Binary Search Tree	108	Easy
14	Unique Binary Search Trees II	95	Medium
15	Sum of Distances in Tree	834	Hard
16	Operations on Tree	1993	Medium
17	Binary Tree Zigzag Level Order Traversal	103	Medium
18	Construct Binary Tree from Preorder and Inorder Traversal	105	Medium
19	Kth Smallest Element in a BST	230	Medium
20	Binary Tree Inorder Traversal	94	Easy
21	Subtree of Another Tree	572	Easy
22	Diameter of Binary Tree	543	Easy
23	Construct Binary Search Tree from Preorder Traversal	1008	Medium
24	Path Sum III	437	Medium
25	Cousins in Binary Tree	993	Easy
26	Count Complete Tree Nodes	222	Medium
27	Invert Binary Tree	226	Easy
28	Sum Root to Leaf Numbers	129	Medium
29	Sum of Left Leaves	404	Easy
30	Unique Binary Search Trees	96	Medium
31	Delete Nodes And Return Forest	1110	Medium
32	Find Leaves of Binary Tree	366	Medium
33	Construct Binary Tree from Inorder and Postorder Traversal	106	Medium
34	Delete Node in a BST	450	Medium

Trie

ID	Problem	Leetcode ID	Difficulty
1	Map Sum Pairs	677	Medium
2	Implement Trie (Prefix Tree)	208	Medium
3	Word Search II	212	Hard
4	Number of Valid Words for Each Puzzle	1178	Hard

Two Pointers

ID	Problem	Leetcode ID	Difficulty
1	Swapping Nodes in a Linked List	1721	Medium
2	Merge Strings Alternately	1768	Easy
3	Next Permutation	31	Medium
4	Minimum Adjacent Swaps to Reach the Kth Smallest Number	1850	Medium
5	Maximum Distance Between a Pair of Values	1855	Medium
6	Jump Game VII	1871	Medium
7	Find K Closest Elements	658	Medium
8	Valid Triangle Number	611	Medium
9	Push Dominoes	838	Medium
10	3Sum Closest	16	Medium
11	Trapping Rain Water	42	Hard
12	Minimum Number of Swaps to Make the String Balanced	1963	Medium
13	Remove Duplicates from Sorted Array	26	Easy
14	Rotate Array	189	Medium
15	Intersection of Two Arrays II	350	Easy
16	Intersection of Two Arrays	349	Easy
17	Move Zeroes	283	Easy
18	Reverse String	344	Easy
19	Valid Palindrome	125	Easy
20	Implement strStr()	28	Easy
21	Two Sum IV - Input is a BST	653	Easy
22	Sum of Square Numbers	633	Medium
23	Remove Nth Node From End of List	19	Medium
24	Longest Uncommon Subsequence II	522	Medium
25	Palindrome Linked List	234	Easy
26	Linked List Cycle	141	Easy
27	Merge Sorted Array	88	Easy
28	Reverse Only Letters	917	Easy
29	3Sum	15	Medium
30	Intersection of Two Linked Lists	160	Easy
31	Sort Colors	75	Medium
32	Sort Array By Parity II	922	Easy
33	Partition Array Into Two Arrays to Minimize Sum Difference	2035	Hard
34	Happy Number	202	Easy
35	Reverse Words in a String	151	Medium
36	Expressive Words	809	Medium

Union Find

ID	Problem	Leetcode ID	Difficulty
1	Minimize Hamming Distance After Swap Operations	1722	Medium
2	Count Sub Islands	1905	Medium
3	Making A Large Island	827	Hard
4	Last Day Where You Can Still Cross	1970	Hard
5	GCD Sort of an Array	1998	Hard
6	Number of Islands	200	Medium
7	Path With Minimum Effort	1631	Medium
8	Surrounded Regions	130	Medium
9	Process Restricted Friend Requests	2076	Hard
10	Redundant Connection	684	Medium

Automatically generated using Leet2Git.