Count the Set Bits in a 32-Bit Unsigned Integer
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Given a non-negative integer that fits in 32 unsigned bits, return how many of its bits are 1.
### Function Signature
```python
def count_set_bits(n: int) -> int:
```
### Rules
- `n` is read as an unsigned 32-bit value; return the number of 1 bits among its 32 bits.
- The result is between 0 and 32 inclusive.
### Constraints
- `0 <= n <= 4294967295`, that is, `n <= 2^32 - 1`.
- Inputs above `2^31 - 1` (2147483647) are valid: in a language whose default integer is a signed 32-bit type, the input must be handled as unsigned.
### Examples
**Example 1**
```text
Input: n = 11
Output: 3
```
11 is `1011` in binary.
**Example 2**
```text
Input: n = 2147483648
Output: 1
```
Only the highest of the 32 bits is set.
**Example 3**
```text
Input: n = 4294967295
Output: 32
```
All 32 bits are set.
Overview: A bit-manipulation task that asks how many bits are set to 1 in a 32-bit unsigned integer. It tests understanding of binary representation and bitwise operations, and correct handling of inputs above the signed 32-bit range.
