折半查找法2

import java.util.Scanner;
public class Demo5{
    public static void main(String[] args) {
        int[] array = {3,7,10,11,16,21};
        Scanner scan = new Scanner(System.in);
        System.out.println("请输入：");
        int num = scan.nextInt();
        int start = 0;
        int end = array.length-1;
        int index = -1;
        while(start<=end){
            int middle = (start+end)/2;
            if(num==array[middle]){
                index = middle;
                break;
            }else if(num>array[middle]){
                start = middle+1;
            }else{
                end = middle-1;
            }
        }
        System.out.println(index);
    }
}