344. 反转字符串

344. 反转字符串

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 1：

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

示例 2：

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

提示：

• 1 <= s.length <= 105
• s[i] 都是 ASCII 码表中的可打印字符

解法：题目要求原地修改，因此使用双指针保存当前变量，并交换

class Solution {
    public void reverseString(char[] s) {
        int left = 0, right = s.length-1;
        while (right > left) {
            char head = s[left];
            char tail = s[right];
            s[left++] = tail;
            s[right--] = head; 
        }
    }
}