LeetCode题目：338. Counting Bits

题目原址：点击打开链接 

题目描述：

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 timeO(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.

我的代码：

时间复杂度应该是O（num*log(num))

class Solution {public:    vector<int> countBits(int num) {        vector<int> result;        for(int i=0;i<=num;i++){            int k=i;            int sum=0;            while(k){                int j;                j=k%2;                k=k/2;                if(j==1)sum++;            }            result.push_back(sum);        }        return result;    }};