代码

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

评测结果