LeetCode 344. 反转字符串

https://leetcode-cn.com/problems/reverse-string/

思路:

1. 双指针, 头指针和尾指针
2. 当头指针索引小于尾指针索引时, 交换值

 /**
     * 双指针
     * @param s
     */
    public void reverseString(char[] s) {
        int first = 0;
        int last = s.length - 1;
        while (first < last) {
            char tmp = s[first];
            s[first] = s[last];
            s[last] = tmp;
            first++;
            last--;
        }
    }