Leetcode 191. Number of 1 Bits

Problem

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

Note:

• Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned.
• In Java, the compiler represents the signed integers using 2’s complement notation. Therefore, in Example 3, the input represents the signed integer. -3.

Algorithm

Counting the remainder of division by two.

Code

class Solution:
    def hammingWeight(self, n: int) -> int:
        ans = 0
        while n:
            ans = ans + n % 2
            n = n // 2
        return ans
1
2
3
4
5
6
7