Count Set Bits in a Positive Signed Integer
Company: Google
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: easy
Interview Round: Other
### Problem
Return the number of set bits in the binary representation of a positive integer n, also called its Hamming weight.
```cpp
int hammingWeight(int n);
```
### Examples
```text
Input: n = 42
Output: 3
```
Its binary spelling is 101010.
```text
Input: n = 1024
Output: 1
```
### Constraints
- `1 <= n <= 2147483647`.
### Optional follow-up
How would you optimize a large number of calls?
Overview: Count set bits of the source’s positive signed integer by lowest-bit removal and byte-table reuse for repeated calls.