代码

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

评测结果