代码

#include<bits/stdc++.h>
int binary_search(const unsigned *a, int n, unsigned x)
{
	int l=1,r=n;
while(l<=n){
int mid=(l+r)/2;
if(a[mid]>x)
r=mid-1;
else if(a[mid]<x)
l=mid+1;
else return mid;
}
return 0;
}

评测结果