191. Number of One Bits

class Solution:
    def hammingWeight(self, n: int) -> int:
        ans = 0
        mask = 1
 
        for _ in range(32):
            if mask & n > 0:
                ans += 1
            mask <<= 1
            
        return ans

• a lot of using bitwise operators, including bitshift left and bitwise and.
• we use a mask that always has a one in each position of the 32 bits.
  • for each mask, if our number is above zero when we bitwise and with the mask, we can increment our answer.

math, bit-manipulation