LC191. Number of 1 Bits

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

Complexity

Time: $O(n)$ where $n$ is number of bits
Space: $O(n)$