代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	unsigned l=1,r=n,mid;
	while(r-l>5){
		mid=l+r>>1;
		(a[mid]<x)?(l=mid):(r=mid);
	}
	for(int i=l;i<=r;i++) if(a[i]==x) return i;
}

评测结果