191. Number of 1 Bits

May 5, 2022

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

Example 1: Input: 00000000000000000000000000001011 Output: 3 Explanation: The input binary string 00000000000000000000000000001011 has a total of three ‘1’ bits.

code

class Solution:
    def hammingWeight(self, n: int) -> int:
        return str(bin(n)).count("1")

code

class Solution:
    def hammingWeight(self, n: int) -> int:
        count = 0
        while n:
            count += n & 1
            n = n >> 1
        return count

code

class Solution:
    def hammingWeight(self, n: int) -> int:
        res = 0
        while n != 0:
            res += 1
            n = n & (n-1)
        return res