Number of 1 Bits

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

Example 1:

Input: n = 11 (binary: 1011)
Output: 3

Example 2:

Input: n = 128 (binary: 10000000)
Output: 1

Example 3:

Input: n = 2147483645 (binary: 1111111111111111111111111111101)
Output: 30

Constraints: