package com.java.arraysdemo;
import java.util.Scanner;
//二分法查找，数组需要是有序的。
public class BinarySearch {
    public static void main(String[] args) {
        int [] array = new int[]{-99,-56,-45,-12,12,22,33,56,94};
        boolean flag = true;
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入您需要寻找的数：");
        while(flag){
            int number = scanner.nextInt();    //需要寻找的数
            int first = 0;  //首索引的位置
            int last = array.length;    //尾索引的位置

            while(first <= last){
                int middle = (first + last) / 2;    //定位middle的位置
                if(array[middle] == number){
                    flag = false;
                    System.out.println("所找的数字索引位置为：数组的第"+(middle + 1)+"个位置");
                    break;
                }else if(array[middle] < number){
                    first = middle + 1;
                }else{
                    last = middle - 1;
                }
            }

            if(flag == true){
                System.out.println("未找到需要寻找的数！请重新输入：");
            }
        }
    }
}