Files
cpp-flashcards/org/study_deck_02/dsa/bit-manipulation/0191-number-of-1-bits.org
T
tomatocream 1dec88aaf2 feat: populate note files with problem descriptions and code stubs
Add populate-notes.mjs that fetches problem descriptions and
Python/C++ code stubs from LeetCode's GraphQL API. Populated
all 197 NeetCode 150 note files with:
- Problem description (examples, constraints)
- Python code stub (function signature)
- C++ code stub (function signature + includes)

API responses cached in leetcode/.cache/leetcode/ for instant re-runs.
2026-06-01 17:22:07 +08:00

1.1 KiB

TODO 0191. Number of 1 Bits   easy

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

class Solution:
    def hammingWeight(self, n: int) -> int:

TODO C++

class Solution {
public:
    int hammingWeight(int n) {
        
    }
};