countBits.cpp

/*Given a non negative integer number num. For every numbers i in the range 0 ≤ i ≤ num calculate
the number of 1's in their binary representation and return them as an array.
Example:
For num = 5 you should return [0,1,1,2,1,2].
Follow up:
It is very easy to come up with a solution with run time O(n*sizeof(integer)). But can you do it in linear time O(n) /possibly in a single pass?
Space complexity should be O(n).
Can you do it like a boss? Do it without using any builtin function like __builtin_popcount in c++ or in any other language.*/

//my Solution 
class Solution {
public:
    vector<int> countBits(int num) {
        vector<int> vi;
        int cnt,n;
        for(int i=0;i<=num;i++)
        {
            n=i;
            cnt=0;
            while(n)
            {
                n=n&(n-1);
                cnt++;
            }
            vi.push_back(cnt);
        }
        return vi;
    }
};