Divide two integers without using multiplication, division and mod operator. http://leetcode.com/onlinejudge#question_29

leetcode_divide_two_integers.cpp

long long f[32];
long long g[32];
class Solution {
public:
    int divide(int dd, int dr) {
        long long divisor = dr, dividend = dd;
        int flag = 1;
        if (divisor < 0) {
            divisor = -divisor;
            flag *= -1;
        }
        if (dividend < 0) {
            dividend = -dividend;
            flag *= -1;
        }
        f[0] = divisor;
        g[0] = 1;
        int n = 0;
        while (dividend - f[n] >= f[n]) {
            n++;
            f[n] = f[n - 1] + f[n - 1];
            g[n] = g[n - 1] + g[n - 1];
        }
        long long ans = 0;
        for (int i = n; i >= 0; --i) {
            if (dividend >= f[i]) {
                ans += g[i];
                dividend -= f[i];
            }
        }
        return ans * flag;
    }
};