class Solution(object):
# def hammingWeight(self, n):
# """
# :type n: int
# :rtype: int
# """
# # using bin
# s_n = bin(n)[2:]
# return s_n.count('1')
def hammingWeight(self, n):
"""
:type n: int
:rtype: int
"""
# https://leetcode.com/articles/number-1-bits/
count = 0
while n:
n &= n - 1
count += 1
return count
