二分法查找

前提条件，已经排好序，由低到高

package com.array;

import java.util.Arrays;

public class TestBinarySearch {

    public static void main(String[] args) {
        int[] arr={30,20,50,10,80,9,7,12,100,40,8};
        Arrays.sort(arr);
        System.out.println(Arrays.toString(arr));
        System.out.println(myBinarySearch(arr,40));
    }
        public static int myBinarySearch(int[] arr,int value){
            int low=0;
            int height=arr.length-1;
            
            while(low<=height){
                int mid=(low+height)/2;
                if(value==arr[mid]){
                    return mid;
                }
                if(value>arr[mid]){
                    low=mid+1;
                }
                if(value<arr[mid]){
                    height=mid-1;
                }
            }
            return -1;
        }
    

}

[7, 8, 9, 10, 12, 20, 30, 40, 50, 80, 100]
7