SquareRoot Here is a very awesome code to find sqrt and even faster than original sqrt function.

mySqrt.cpp

#include "iostream"
#define EPSILON 0.0000001 // least minimum value for comparison

using namespace std;

class Solution {
public:
    int mySqrt(double x) {
        if (x <= 0)
            return 0;

        double s = x;

        while ((s - x / s) > EPSILON)
            s = (s + x / s) / 2;

        return static_cast<int>(s);
    }
};

int main()
{
    Solution solution;
    cout << solution.mySqrt(4) << std::endl;
    cout << solution.mySqrt(64) << std::endl;
    cout << solution.mySqrt(994009) << std::endl;
    cout << solution.mySqrt(996004) << std::endl;
    cout << solution.mySqrt(998001) << std::endl;
    cout << solution.mySqrt(1000000) << std::endl;
    cout << solution.mySqrt(2147483647) << std::endl;
    return 0;
}

square_root.cpp

float InvSqrt (float x) 
{
    float xhalf = 0.5f*x;
    int i = *(int*)&x;
    i = 0x5f375a86 - (i>>1);
    x = *(float*)&i;
    x = x*(1.5f - xhalf*x*x);
    x = x*(1.5f - xhalf*x*x);
    x = x*(1.5f - xhalf*x*x);
    x=1/x;
    return x;
}

Finding square root without using sqrt function?