[leetcode] p338 Count Bits

class Solution {
public:
    vector<int> countBits(int num) {

        vector<int> result;

        for (int i=0; i<num+1; i++)
        {
            if (i==0)
            {
                result.push_back(0);
            }
            else
            {
                result.push_back(result.at(i >> 1) + (i & 1));
            }

        }

        return result;
    }
};