Simple and 4 lines

  • 20
    class Solution {
        vector<int> countBits(int num) {
            vector<int> res(num+1,0);
            for(int i = 1; i < res.size();i++)
                res[i] = i%2 + res[i/2];
            return res;

  • 1

    I like the answer. It makes lot of sense.
    I personally did it a bit cheaper way but a dynamic programming is better.
    Here is what I did in Python:

    class Solution(object):
        def countBits(self, num):
            :type num: int
            :rtype: List[int]
            arr = []
            for i in range(num+1):
                binary = bin(i)[2:]
                ones = binary.replace("0","")
                count = len(ones)
            return arr

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