leetcode. Sqrt(x)

int sqrt(int x) 
    {
        unsigned long long low = 0, high = x / 2 + 1, mid = 0;
        while (low <= high)
        {
            mid = (low + high) / 2;
            if (mid * mid == x)
            {
                break;
            }
            else if (mid * mid < x)
            {
                low = mid + 1;
            }
            else
            {
                high = mid - 1;
            }
        }
            
        return mid * mid > x ? mid - 1 : mid;
    }