代码

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

评测结果