代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	int l=0,r=n-1;
	while(l<=r){
		int md=(l+r)/2;
		if(a[md]<x){
			r=md-1;
		}else if(a[md]==x){
			return md;
		}else{
			l=md+1;
		}
	}
}

评测结果