算法天天练334：字符串翻转

题目来源： https://leetcode.com/problems/reverse-string/
问题描述： 颠倒一个char数组里面的字符串顺序，只能修改原始数组的值，不允许分配额外的空间。
举例说明：

输入	输出
["h","e","l","l","o"]	["o","l","l","e","h"]
["H","a","n","n","a","h"]	["h","a","n","n","a","H"]

解决方案

1. 遍历数组后用中间变量交换元素位置，时间复杂度Ο(n)

class Solution {
    public void reverseString(char[] s) {
        int length = s.length;
        for(int i=0;i