数据结构——二分查找（1）

import java.util.Scanner;

public class Main {
    
     public static int[] a = new int[10];
    
    public static void main(String[] args) {
       
     
       Scanner s = new Scanner(System.in);
       int n = s.nextInt();
       int b = s.nextInt();
       for(int i = 0; i < n; i++){
           a[i] = s.nextInt();
       }
     
       System.out.print( basic(a,b));
    }
    
    public static int basic(int[] a, int tar){   //升序数值，找到对应值的下标
           int i = 0 , j = a.length - 1;
           while(i <= j){
               int m = i + j >> 1;  //下标取整，3.5 => 3
               if(tar > a[m]){   //目标在右边
                   i = m + 1;
               }else if(tar < a[m]){   //目标在左边
                   j = m -1;
               }else{  
                   return m;
               }
           }
           return -1;
       }
}