LeetCode题解(0917)：翻转字符串中的字母(Python)

题目：原题链接（简单）

标签：字符串、双指针

解法时间复杂度空间复杂度执行用时Ans 1 (Python)$O(N)$$O(1)$36ms (89.63%)Ans 2 (Python)$O(N)$$O(1)$44ms (46.19%)Ans 3 (Python)

解法一（双指针）：

def reverseOnlyLetters(self, S: str) -> str: S = list(S) idx1 = 0 idx2 = len(S) - 1 while idx1 < idx2: if not S[idx1].isalpha(): idx1 += 1 elif not S[idx2].isalpha(): idx2 -= 1 else: S[idx1], S[idx2] = S[idx2], S[idx1] idx1 += 1 idx2 -= 1 return "".join(S)

解法二（反转指针）：

def reverseOnlyLetters(self, S: str) -> str: idx = len(S) - 1 ans = "" for s in S: if s.isalpha(): while idx >= 0 and not S[idx].isalpha(): idx -= 1 ans += S[idx] idx -= 1 else: ans += s return ans