#+ANKI_DECK: study_deck_02
* TODO 0191. Number of 1 Bits :easy:
:PROPERTIES:
:NEETCODE: [[file:../../roadmap.org::*0191. Number of 1 Bits][0191. Number of 1 Bits]]
:END:

Given a positive integer ~n~, write a function that returns the number of set bits in its binary representation (also known as the Hamming weight).

*Example 1:*

*Input:* n = 11

*Output:* 3

*Explanation:*

The input binary string *1011* has a total of three set bits.

*Example 2:*

*Input:* n = 128

*Output:* 1

*Explanation:*

The input binary string *10000000* has a total of one set bit.

*Example 3:*

*Input:* n = 2147483645

*Output:* 30

*Explanation:*

The input binary string *1111111111111111111111111111101* has a total of thirty set bits.

*Constraints:*

 - ~1 <= n <= 2^{31} - 1~

*Follow up:* If this function is called many times, how would you optimize it?

** TODO Approach
Write your approach here.

** TODO Python
#+begin_src python
class Solution:
    def hammingWeight(self, n: int) -> int:
#+end_src

** TODO C++
#+begin_src cpp
class Solution {
public:
    int hammingWeight(int n) {
        
    }
};
#+end_src