Elimination Game Solutions in C++

// Source : https://leetcode.com/problems/elimination-game
// Author : Hao Chen
// Date   : 2016-09-07-



class Solution {
public:
    int lastRemaining(int n) {
        int start = 1, step = 1;
        while (n > 1) {
            start += step + (n-2)/2 * 2*step;
            n /= 2;
            step *= -2;
        }
        return start;
    }
};

/// Source : https://leetcode.com/problems/elimination-game/description/
/// Author : liuyubobobo
/// Time   : 2017-10-27

#include <iostream>

using namespace std;

class Solution {
public:
    int lastRemaining(int n) {

        if(n == 1)
            return 1;

        return 2 * (1 + n/2 - lastRemaining(n/2));
    }
};

int main() {

    cout << Solution().lastRemaining(9) << endl;

    return 0;
}