使用递归算法实现冒泡：

 

package com.nami.algorithm.study.day06;import java.util.Arrays;/*** beyond u self and trust u self.** @Author: lbc* @Date: 2023-09-05 15:36* @email: 594599620@qq.com* @Description: keep coding*/
public class BubbleSort2 {//    public static void sort(int[] target, int num) {
//        if (num == 0) {
//            return;
//        }
//        bubble(target, num-1);
//
//        sort(target, num-1);
//    }
//
//    private static void bubble(int[] target, int j) {
//        for (int i = 0; i < j; i++) {
//            if (target[i] > target[i + 1]) {
//                int temp = target[i];
//                target[i] = target[i+1];
//                target[i+1] = temp;
//            }
//        }
//    }public static void sort(int[] target) {bubble(target, target.length -1 );}private static void bubble(int[] target, int j) {if (j == 0) {return;}for (int i = 0; i < j; i++) {if (target[i] > target[i + 1]) {int temp = target[i];target[i] = target[i+1];target[i+1] = temp;}}bubble(target, j - 1);}public static void main(String[] args) {int[] test = new int[]{1, 54, 234, 675, 32432, 23, 78, 459, 354, 9, 344, 22, 46, 85, 236, 3278, 245, 83, 154, 2, 1, 34, 73, 23};int[] test2= new int[] {2,4,7,3,2,1};
//        sort(test, test.length);sort(test2);System.out.println(Arrays.toString(test2));}}

优化数组稳定得情况, 减少无意义遍历，新增参数x, 标识是否发生了挪动，递归时使用x索引，非常巧妙。递归妙

package com.nami.algorithm.study.day06;import java.util.Arrays;/*** beyond u self and trust u self.** @Author: lbc* @Date: 2023-09-05 15:36* @email: 594599620@qq.com* @Description: keep coding*/
public class BubbleSort {public static void sort(int[] target) {bubble(target, target.length -1 );}private static void bubble(int[] target, int j) {if (j == 0) {return;}// 变换标识 索引iint x = 0;for (int i = 0; i < j; i++) {if (target[i] > target[i + 1]) {int temp = target[i];target[i] = target[i+1];target[i+1] = temp;x = i;}}bubble(target, x);}public static void main(String[] args) {int[] test = new int[]{1, 54, 234, 675, 32432, 23, 78, 459, 354, 9, 344, 22, 46, 85, 236, 3278, 245, 83, 154, 2, 1, 34, 73, 23};int[] test2= new int[] {2,4,7,3,2,1};
//        sort(test, test.length);sort(test2);System.out.println(Arrays.toString(test2));}}