【Arai60】53問目 22. Generate Parentheses

arai60/50-53_Greedy_Backtracking/53_22_Generate Parentheses/level_1.py

@@ -0,0 +1,21 @@
+# backtracking
+class Solution:
+    def generateParenthesis(self, n: int) -> List[str]:
+        def make_combination(current):
+            if remain["("] > remain[")"]:
+                return
+            if remain["("] < 0:
+                return
+            if remain[")"] == 0:
+                parentheses.append(current)
+                return
+            for bracket in brackets:
+                remain[bracket] -= 1
+                make_combination(current + bracket)
+                remain[bracket] += 1
+
+        brackets = ["(", ")"]
+        remain = {"(": n, ")": n}
+        parentheses = []
+        make_combination("")
+        return parentheses

arai60/50-53_Greedy_Backtracking/53_22_Generate Parentheses/level_2.py

@@ -0,0 +1,16 @@
+# backtracking
+# 括弧の数を引数にする
+class Solution:
+    def generateParenthesis(self, n: int) -> List[str]:
+        def make_combination(current, remain_left, remain_right):
+            if remain_left == 0 and remain_right == 0:
+                parentheses.append(current)
+                return
+            if 0 < remain_left:
+                make_combination(current + "(", remain_left - 1, remain_right)
+            if remain_left < remain_right:
+                make_combination(current + ")", remain_left, remain_right - 1)
+
+        parentheses = []
+        make_combination("", n, n)
+        return parentheses

arai60/50-53_Greedy_Backtracking/53_22_Generate Parentheses/level_3.py

@@ -0,0 +1,14 @@
+class Solution:
+    def generateParenthesis(self, n: int) -> List[str]:
+        def make_combination(current, remain_left, remain_right):
+            if remain_left == 0 and remain_right == 0:
+                parentheses.append(current)
+                return
+            if 0 < remain_left:
+                make_combination(current + "(", remain_left - 1, remain_right)
+            if remain_left < remain_right:
+                make_combination(current + ")", remain_left, remain_right - 1)
+
+        parentheses = []
+        make_combination("", n, n)
+        return parentheses

arai60/50-53_Greedy_Backtracking/53_22_Generate Parentheses/level_4.py

@@ -0,0 +1,34 @@
+class Solution:
+    def generateParenthesis(self, n: int) -> List[str]:
+        stack = [("", n, n)]
+        parentheses = []
+        while stack:
+            current, remain_left, remain_right = stack.pop()
+            if remain_left == 0 and remain_right == 0:
+                parentheses.append(current)
+                continue
+            if 0 < remain_left:
+                stack.append((current + "(", remain_left - 1, remain_right))
+            if remain_left < remain_right:
+                stack.append((current + ")", remain_left, remain_right - 1))
+
+        return parentheses
+
+
+# backtracking
+# 関数内で使う変数は先に定義する
+class Solution:
+    def generateParenthesis(self, n: int) -> List[str]:
+        parentheses = []
+
+        def make_combination(current, remain_left, remain_right):
+            if remain_left == 0 and remain_right == 0:
+                parentheses.append(current)
+                return
+            if 0 < remain_left:
+                make_combination(current + "(", remain_left - 1, remain_right)
+            if remain_left < remain_right:
+                make_combination(current + ")", remain_left, remain_right - 1)
+
+        make_combination("", n, n)
+        return parentheses