算法：

冒泡排序

选择排序

二分查找

1. 冒泡排序

1.1 定义

1.2 代码示例

Java业务逻辑-1(冒泡排序)-CSDN博客https://blog.csdn.net/XiaomeiGuiSnJs/article/details/140880229

2. 选择排序

2.1 定义

2.2 代码示例

package cn.hdc.itWork.d5.d2;

import java.util.Arrays;

//选择排序
public class t2 {
    public static void main(String[] args) {
        int[] arr = {5, 2, 3, 1};
        for (int i = 0; i < arr.length; i++) {
            int minIndex = i;
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[i] > arr[j]) {
                    minIndex = j;
                }
            }
            int temp = arr[i];
            arr[i] = arr[minIndex];
            arr[minIndex] = temp;
        }
        System.out.println(Arrays.toString(arr));
    }
}

3. 二分查找

3.1 定义

3.2 代码示例

package cn.hdc.itWork.d5.d2;

import java.util.Scanner;

//二分查找
public class t3 {
    public static void main(String[] args) {
        int u = u();
        System.out.println(u);
    }

    public static int u() {
        int[] arr = {7, 23, 79, 81, 103, 127, 131, 147};
        int start = 0;
        int end = arr.length - 1;
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        if (num < arr[0] || num > arr[arr.length - 1]) {
            return -1;
        }
        while (start <= end) {
            int mid = (start + end) / 2;
            if (num == arr[mid]) {
                return mid;
            } else if (num > arr[mid]) {
                start = mid + 1;
            } else {
                end = mid - 1;
            }
        }
        return -2;
    }
}

4. 方法递归

Java算法__递归-CSDN博客https://blog.csdn.net/XiaomeiGuiSnJs/article/details/141816321