#Write a function that takes an unsigned integer and returns the number of ’1' bits it has
#For example, the 32-bit integer ’11' has binary representation 00000000000000000000000000001011, so the function should return 3.

class Solution:
  def hammerweight(self,n):
    res = 0
    while n:
      n &= n -1
      res += 1
    return res
