【LeeCode】344. 反转字符串

【题目描述】

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。

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

【示例】

【代码】

这里主要是for循环里的变量都是数组的下标

package com.company;
import java.util.Arrays;

public class Solution {
    public static void main(String[] args) {
        char[] s = {'h','e','l','l','o'};
        reverseString(s);
    }

    public static  void reverseString(char[] s) {
        System.out.println(Arrays.toString(s));
        int len = s.length;
        for(int left = 0, right = len - 1; left < right; ++left, --right){
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
        }
        System.out.println(Arrays.toString(s));
    }
}

​​学习参考​​

【代码2】

​​学习参考​​

package com.company;
import java.util.Arrays;

public class Solution {
    public static void main(String[] args) {
        char[] s = {'h','e','l','l','o'};
        reverseString2(s);
    }

    public static  void reverseString2(char[] s) {
       int left = 0;
       int right = s.length - 1;
       while (left < right){
           char c = s[left];
           s[left] = s[right];
           s[right] = c;
           left++;
           right--;
       }
        System.out.println(Arrays.toString(s));
    }
}

【代码】​​双指针​​

package com.company;
import java.util.*;

// 2022-02-18
class Solution {
    public void reverseString(char[] s) {
        int len = s.length;
        for(int left = 0, right = len - 1; left < right; ++left, --right){
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
        }
        System.out.println(Arrays.toString(s));
        System.out.println(Arrays.toString(s));
    }
}

public class Test {
    public static void main(String[] args) {
        new Solution().reverseString(new char[]{'h', 'e', 'l', 'l', '0'}); // 输出：["o","l","l","e","h"]
        new Solution().reverseString(new char[]{'2', '0', '2', '3'}); // 输出：['3', '2', '0', '2']
    }
}

package com.company;
import java.util.*;

// 2022-02-18
class Solution {
    public void reverseString(char[] s) {
        int left = 0;
        int right = s.length - 1;
        while (left < right){
            char tmp = s[left];
            s[left] = s[right];
            s[right] = tmp;
            left++;
            right--;
        }

        System.out.println(Arrays.toString(s));
        System.out.println(Arrays.toString(s));
    }
}

public class Test {
    public static void main(String[] args) {
        new Solution().reverseString(new char[]{'h', 'e', 'l', 'l', '0'}); // 输出：["o","l","l","e","h"]
        new Solution().reverseString(new char[]{'2', '0', '2', '3'}); // 输出：['3', '2', '0', '2']
    }
}