【Arai60】57問目 392. Is Subsequence

arai60/54-60_others/57_392_Is Subsequence/level_1.py

@@ -0,0 +1,14 @@
+# ポインタを2つ用意して、同じ文字ならsを次に進める
+# sが最後まで進めばSubsequenceが存在する
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        t_index = 0
+        for s_index in range(len(s)):
+            if len(t) <= t_index:
+                return False
+            while t[t_index] != s[s_index]:
+                t_index += 1
+                if len(t) == t_index:
+                    return False
+            t_index += 1
+        return True

arai60/54-60_others/57_392_Is Subsequence/level_2.py

@@ -0,0 +1,30 @@
+# ポインタを2つ用意して、同じ文字ならsを次に進める
+# while文で記載
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        t_index = 0
+        s_index = 0
+        while s_index < len(s) and t_index < len(t):
+            if s[s_index] == t[t_index]:
+                s_index += 1
+            t_index += 1
+        return s_index == len(s)
+
+
+# DPで最長共通部分列問題を解く
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        # longest_common_nums[i][j]はs[:i]とt[:j]の最長共通部分列の長さ
+        longest_common_nums = [[0] * (len(t) + 1) for _ in range(len(s) + 1)]
+        for i in range(len(s)):
+            for j in range(len(t)):
+                if s[i] == t[j]:
+                    longest_common_nums[i + 1][j + 1] = (
+                        longest_common_nums[i][j] + 1
+                    )
+                    continue
+                longest_common_nums[i + 1][j + 1] = max(
+                    longest_common_nums[i + 1][j],
+                    longest_common_nums[i][j + 1],
+                )
+        return longest_common_nums[-1][-1] == len(s)

arai60/54-60_others/57_392_Is Subsequence/level_3.py

@@ -0,0 +1,9 @@
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        s_index = 0
+        t_index = 0
+        while s_index < len(s) and t_index < len(t):
+            if s[s_index] == t[t_index]:
+                s_index += 1
+            t_index += 1
+        return s_index == len(s)

arai60/54-60_others/57_392_Is Subsequence/level_4.py

@@ -0,0 +1,22 @@
+# ポインタを2つ用意して、同じ文字ならsを次に進める
+# sが最後まで進めばSubsequenceが存在する
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        t_index = 0
+        for s_index in range(len(s)):
+            for t_index in range(t_index, len(t)):
+                if t[t_index] == s[s_index]:
+                    t_index += 1
+                    break
+            else:
+                return False
+        return True
+
+
+# 正規表現
+class Solution:
+    def isSubsequence(self, s: str, t: str) -> bool:
+        pattern = ""
+        for c in s:
+            pattern += ".*" + c
+        return re.match(pattern, t) != None