LeetCode/src/main/java/L0344_ReverseString.java at master · LjyYano/LeetCode · GitHub

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/**

* https://leetcode.cn/problems/reverse-string/

* 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

public class L0344_ReverseString {

public void reverseString(char[] s) {

// 使用双指针，从两端向中间移动

int left = 0, right = s.length - 1;

// 当左指针小于右指针时，交换两个字符

while (left < right) {

// 交换字符

char temp = s[left];

s[left] = s[right];

s[right] = temp;

// 移动指针

left++;

right--;

}

public static void main(String[] args) {

L0344_ReverseString solution = new L0344_ReverseString();

// 测试用例 1

char[] s1 = {'h', 'e', 'l', 'l', 'o'};

System.out.print("测试用例 1 反转前：");

printArray(s1);

solution.reverseString(s1);

System.out.print("测试用例 1 反转后：");

printArray(s1);

// 测试用例 2

char[] s2 = {'H', 'a', 'n', 'n', 'a', 'h'};

System.out.print("测试用例 2 反转前：");

printArray(s2);

solution.reverseString(s2);

System.out.print("测试用例 2 反转后：");

printArray(s2);

}

// 辅助方法：打印字符数组

private static void printArray(char[] arr) {

System.out.print("[");

for (int i = 0; i < arr.length; i++) {

System.out.print("'" + arr[i] + "'");

if (i < arr.length - 1) {

System.out.print(",");

}

System.out.println("]");

}

LeetCode/src/main/java/L0344_ReverseString.java at master · LjyYano/LeetCode · GitHub

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