Counting Bits（Difficulty: Medium）

題目：

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].

實現：

 1 class Solution {  2 public:  3     vector<int> countBits(int num) {  4    vector<int> result;  5     for (int i = 0; i <= num; i++)  6  {  7         int count = 0;  8         int j = i;  9         while (j) 10  { 11             ++count; 12             j = (j-1) & j; 13  } 14  result.push_back(count); 15  } 16     return result; 17  } 18 };