折半查找/冒泡查找

一、折半查找

/**
 * Created with Intellij IDEA
 * ClassName:BinarySearch
 * User:MaLe
 * Description:给定一个有序整型数组, 实现二分查找
 * @Date:2021/10/16
 * @Time:15:51
 * @author:395645313@qq.com
 */
public class BinarySearch {
    public static int binarySearch(int[] arr,int n){
      int i=0;
      int j=arr.length-1;
      while (i<=j) {
          int mid=(i+j)/2;
          if (n < arr[mid]) {
              j=mid-1;
          } else if (n > arr[mid]) {
              i=mid+1;
          } else if (n == arr[mid]) {
              return mid;
          }
      }
      return -1;
    }

    public static void main(String[] args) {
        int[] arr={1,2,3,4,5,6,7,8,9};
        int a=binarySearch(arr,9);
        System.out.println(a);
    }

}

二、冒泡排序

import java.util.Arrays;

/**
 * Created with Intellij IDEA
 * ClassName:Bubble
 * User:MaLe
 * Description:给定一个整型数组, 实现冒泡排序(升序排序)
 * @Date:2021/10/16
 * @Time:15:17
 * @author:395645313@qq.com
 */
public class Bubble {
    public static int[] bub(int[] arr){
        int a=0;
        for (int i = 0; i <arr.length-1 ; i++) {
            boolean flag=false;
            for (int j = 0; j <arr.length-1-i ; j++) {
                if (arr[j]>arr[j+1]){
                    a=arr[j];
                    arr[j]=arr[j+1];
                    arr[j+1]=a;
                    flag=true;
                }
            }
            if (flag=false){
                return arr;
        }
        }
        return arr;
    }
    public static void main(String[] args) {
        int[] arr={1,9,5,8,4,78};
        System.out.println("排序前:");
        System.out.println(Arrays.toString(arr));
        int[] c=bub(arr);
        System.out.println("排序后:");
        System.out.println(Arrays.toString(c));
    }
}