*用递归写个二分查找；*

用递归写个二分查找；

package CL6;

import java.util.Scanner;

/**
 * @author: 贾兴伟
 * @date: Created in 20:00 2020/9/22
 */
public class BinarySearch {
    public static int BinarySearched(int[] arr,int beginIndex,int endIndex,int value){
//        int left = beginIndex,right = endIndex,might;
//        while(left<=right) {
//            might=((right-left)>>>2)+left;
//            if (arr[might] < value) {
//                left = might + 1;
//            }else if (arr[might] > value) {
//                right = might - 1;
//            }else {
//                return might;
//            }
//        }
//        return -1;
        int mid = ((endIndex-beginIndex)>>>1)+beginIndex;
        if(beginIndex>endIndex){
            return  -1;
        }
        if(arr[mid]==value){
            return mid;
        }else if(arr[mid]>value){
            return BinarySearched(arr,beginIndex,mid-1,value);
        }else {
            return BinarySearched(arr, mid + 1, endIndex, value);
        }
    }

    public static void main(String[] args) {
        int[] arr = {1,3,5,7,8,9};
        System.out.println("请输入一个数字");
        Scanner scanner = new Scanner(System.in);
        int value= scanner.nextInt();
        int a =BinarySearched(arr,0,arr.length-1,value);
        System.out.println(a);
    }
}