代码

int binary_search(const unsigned * const a, const int n, const unsigned x) {
	unsigned l=0,r=n-1;
	for(;l<r;){
		const unsigned m=(l+r)>>1;
		const unsigned v=a[m];
		if(v==x)return m;
		else if(v<x){
			l=m+1;
		}else{
			r=m-1;
		}
	}
	return l;
}

评测结果