折半查找

#include<iostream>
using namespace std;
int main()
{
    int a[10]={1,2,3,4,5,21,34,45,115,4121};
    int f,tail=0,top=9,mid=(top+tail)/2;
    int n;
    cout<<"请输入要查找的数："<<endl;
    cin>>n;
    while(1)
    {
        if(n==a[mid])
        {
            cout<<"yes!!!\n";
            break;
        }

        else if(n<a[mid-1])
        {
            tail=tail;
            top=mid-1;
            mid=(top+tail)/2;
        }
        else
        {
            top=top;
            tail=mid+1;
            mid=(top+tail)/2;

        }
        if (tail>top)
        {
            cout<<"No!!!\n";
            break;
        }
    }
   return 0;
}