Divide two integers without using multiplication, division and mod operator. http://leetcode.com/onlinejudge

leetcode_divide_two_integers.cpp

class Solution {
public:
    int divide(int dividend_, int divisor_) {
        long long dividend = dividend_, divisor = divisor_;
        int flag = 1;
        if (dividend < 0) {
            flag *= -1;
            dividend = -dividend;
        }
        if (divisor < 0) {
            flag *= -1;
            divisor = - divisor;
        }
        long long f[50], g[50];
        int n = 1;
        for (n = 1; ; ++n) {
            if (n == 1) {
                f[1] = divisor;
                g[1] = 1;
            }
            else {
                f[n] = f[n - 1] + f[n - 1];
                g[n] = g[n - 1] + g[n - 1];
            }
            if (dividend - f[n] < f[n])
                break;
        }
        int ret = 0;
        for (int i = n; i >= 1; --i)
            if (dividend >= f[i]) {
                dividend -= f[i];
                ret += g[i];
            }
        return ret * flag;
    }
};