LeetCode C++ 344. Reverse String【String】简单

Write a function that reverses a string. The input string is given as an array of characters char[] .

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

You may assume all the characters consist of printable ascii characters.

Example 1:

Input: ["h","e","l","l","o"] Output: ["o","l","l","e","h"]

Example 2:

Input: ["H","a","n","n","a","h"] Output: ["h","a","n","n","a","H"]

题意：编写一个函数，其作用是将输入的字符串反转过来。要求必须原地修改输入数组、使用 $O(1)$ 的额外空间解决这一问题。

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解法一 STL

使用万能的STL大法：

class Solution { public: void reverseString(vector<char>& s) { reverse(s.begin(), s.end()); } };

效率如下：

执行用时：56 ms, 在所有 C++ 提交中击败了68.97% 的用户 内存消耗：22.7 MB, 在所有 C++ 提交中击败了48.85% 的用户

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解法二

很简单的代码：

class Solution { public: void reverseString(vector<char>& s) { for (int i = 0, j = s.size() - 1; i < j; ++i, --j) swap(s[i], s[j]); } };

结果如下：

执行用时：56 ms, 在所有 C++ 提交中击败了68.97% 的用户 内存消耗：22.8 MB, 在所有 C++ 提交中击败了37.87% 的用户