代码

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

评测结果