原题出处：https://leetcode.cn/leetbook/read/top-interview-questions-easy/xnhbqj/

解法一：

 public void reverseString(char[] s) {
        int length = s.length/2;
        for (int i = 0; i < length; i++) {
            char tmp = s[i];
            s[i] = s[s.length-1-i];
            s[s.length-1-i] = tmp;
        }
    }

思路：将字符数组分为两半，前一半与后一半的值进行交换即可。