ReverseString.java

package leetcode.two_pointers;

/**
 * @description 344. 反转字符串
 * @author chengzw
 * @link https://leetcode.cn/problems/reverse-string/
 * <p>
 * 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。
 * <p>
 * 示例 1：
 * 输入：s = ["h","e","l","l","o"]
 * 输出：["o","l","l","e","h"]
 * <p>
 * 示例 2：
 * 输入：s = ["H","a","n","n","a","h"]
 * 输出：["h","a","n","n","a","H"]
 * @since 2022/6/6
 */

/**
 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"]
 */

/**
 思路：双指针
 1.指针 left 从左往右遍历，指针 right 从右往左遍历
 2.交换 left 和 right 的元素

 时间复杂度：O(n)
 空间复杂度：O(1)
 */
public class ReverseString {
    public void reverseString(char[] s) {
        for (int left = 0, right = s.length - 1; left < right; left++, right--) {
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
        }
    }
}