new_contents: 
  # O(n * sizeof(n)) solution
  class Solution(object):
      def countBits(self, num):
          ret = [0]*(num+1)
          for i in range(0, num+1):
              curr = i
              while (i != 0):
                  ret[curr] += i & 1
                  i >>= 1
          return ret
  
  
  class Solution(object):
      def countBits(self, num):
          ret = [0]*(num+1)
          
  
subject: Add 338-counting-bits.py