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l191 number of 1 bits

admin 11月 13, 2020 0

题目描述

Write a function that takes an unsigned integer and returns the number of ’1' bits 
it has (also known as the Hamming weight).

For example, the 32-bit integer ’11' 
has binary representation 00000000000000000000000000001011, 
so the function should return 3.

解题思路

计算二进制，判断当前是否需要计数
使用n&n-1

Python实现

class (object):
    def hammingWeight(self, n):
        """
        :type n: int
        :rtype: int
        """
        count = 0
        while n>0:
            if n%2:
                count +=1
            n /= 2
        return count

Python实现

class (object):
    def hammingWeight(self, n):
        """
        :type n: int
        :rtype: int
        """

        count = 0

        while n>0:
            n = n &(n-1)
            count+=1
        return count