需求

编写一个函数，其作用是将输入的字符串反转过来。输入字符串以字符数组 s的形式给出。
不要给另外的数组分配额外的空间，你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。

示例

输入：s = ["h","e","l","l","o"]
输出：["o","l","l","e","h"]

输入：s = ["H","a","n","n","a","h"]
输出：["h","a","n","n","a","H"]

思路

双指针前后遍历，当指针遇到一起跳出循环

代码

public void reverseString(char[] s) {
        int i=0,j=s.length-1;
        while(i<j){
            char temp=s[i];
            s[i++]=s[j];
            s[j--]=temp;
        }
    }