Integer Square Root

gistfile1.cs

public static int IntSqrt(int num) // Faster than Math.Sqrt, because that uses doubles.
{
    if (num < 0) throw new Exception("Cannot get square root of negative number.");
    if (0 == num) return 0; // Avoid zero divide
    int n = (num / 2) + 1; // Initial estimate, never low
    int n1 = (n + (num / n)) / 2;
    while (n1 < n)
    {
        n = n1;
        n1 = (n + (num / n)) / 2;
    }
    return n;
}

Found a C++ version of this: https://github.com/justicezyx/interview/blob/master/squareroot.cpp#L154