Python3 代码

class Solution(object):
    def NumberOf1(self,n):
        """
        :type n: int
        :rtype: int
        """
        re = []

        t = abs(n)
        while t :
            re.append(t % 2)
            t //= 2

        if n >= 0:
            return re.count(1)
        else:
            num = 32 - len(re)
            return num + re.count(1)