代码

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

评测结果