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
1 /**
2 * Return an array of size *returnSize.
3 * Note: The returned array must be malloced, assume caller calls free().
4 */
5 int* countBits(int num, int* returnSize) {
6 int *ary;
7 int i;
8 int k;
9 ary = (int *)malloc((num + 1) * sizeof(int));
10 for(i = 0; i <= num; i++)
11 {
12 ary[i] = 0;
13 k = i;
14 while(k)
15 {
16 k &= (k-1);
17 ary[i]++;
18 }
19 }
20 *returnSize = num + 1;
21 return ary;
22 }