插值查找C++

#include <iostream>
using namespace std;
//需要有序数组，最好是均匀分布的。
int binary_search(int *A,int n,int key)
{
    int left=0,right=n-1;
    while(left<=right)
    {
        int mid= left + (int)(1.0*(key-A[left]))/(A[right]-A[left])*(right-left);
        if(key==A[mid])
            return mid;
        else if(key<A[mid])
            right=mid-1;
        else
            left=mid+1;
    }
    return -1;
}

int main()
{
    int A[8]={4,7,9,12,15,34,36,67};
    int key;cin>>key;
    cout<<binary_search(A,8,key);
    return 0;
}