二分查找

#include <cstdio>
#include <iostream>
#include<string>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
int n;
int a[105];
int m;
int x;
bool erfen(int a[],int b)
{
    int low=0;
    int mid;
    int high=n-1;
    while(low<=high)
    {
       mid=(low+high)/2;
       if(b==a[mid])
           return true;
       else
        if(b>a[mid])
       {
            low=mid+1;
            }
      else
    if(b<a[mid])
    {
        high=mid-1;
    }  
    }
    return false; //一开始忘记写了！！一定要写上！！！
}

int main()
{

    while(cin>>n)
    {
        int flag=0;
        for(int i=0;i<n;i++)
          cin>>a[i];
        sort(a,a+n);
        cin>>m; 
        for(int i=0;i<m;i++)
          {
              cin>>x;
              if(erfen(a,x))
              cout<<"YES"<<endl;
              else
              cout<<"NO"<<endl;
          }
        
    }
    return 0;
}