代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	int b[2] = {0, n - 1};
	do
	{
		int mid = (b[0] + b[1]) / 2;
		b[a[mid] >= x] = mid + (a[mid] < x);
	}
	while (b[0] != b[1]);
	return b[0];
}

评测结果