【每日一题】P2249 【深基13.例1】查找

package week1;

import java.util.Scanner;
public class Main2 {
  public static void main(String[] args) {
    Scanner s=new Scanner(System.in);
    int n=s.nextInt();
    int k=s.nextInt();
    int[] arr=new int[n];
    for(int i=0;i<n;i++){
      arr[i]=s.nextInt();
    }
    int key,low,high,mid;
    while (k--!=0){
      key=s.nextInt();
      low=0;
      high=n-1;
      while (low<high){
        mid=(low+high)>>1;
        if(key<=arr[mid]){
          high=mid;
        }else
          low = mid+1 ;
      }
      if(arr[low]==key)
        System.out.print((low+1)+" ");
      else
        System.out.print(-1+" ");
    }
    s.close();
  }
}

Experience
使用做二分查找，只需要key<=arr[mid]就行了