Problem
Given an unsigned integer, count the number of set bits (1s) in its binary representation — the Hamming weight.
Input / Output
- Input: a 32-bit unsigned integer n.
- Output: the count of 1 bits.
Constraints
- 32-bit unsigned input.
- Aim for time proportional to the number of set bits rather than always 32 iterations.
Example
- 11 (0b1011) → 3
- 128 (0b1000_0000) → 1
- 0 → 0