[LeetCode] 344. Reverse String 翻转字符串

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"]

这道题没什么难度，直接从两头往中间走，同时交换两边的字符即可，参见代码如下：

解法一：

class Solution {
public:
    void reverseString(vector<char>& s) {
        int left = 0, right = (int)s.size() - 1;
        while (left < right) {
            char t = s[left];
            s[left++] = s[right];
            s[right--] = t;
        }
    }
};

我们也可以用 swap 函数来帮助我们翻转：

解法二：

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