algoadvance

Write a function that takes an unsigned integer and returns the number of ‘1’ bits it has (also known as the Hamming weight).

Example:

Input: 00000000000000000000000000001011
Output: 3
Explanation: The input binary string has a total of three '1' bits.

Input Type and Format:
- What is the type of input? Is it a binary string or an integer?
- Will the input always have exactly 32 bits?
Expected Output:
- Is the expected output an integer indicating the count of ‘1’ bits?

Once clarified, let’s assume:

Bit Manipulation Approach - Using Python’s Built-in Functions:
- Convert the integer to its binary representation using the bin() function.
- Count the number of ‘1’s in the string representation of the binary number.
Loop and Bitwise Operation Approach:
- Use a loop to repeatedly check the least significant bit and use a right shift to process the number bit by bit.
- Use the bitwise AND operation to check if the least significant bit is ‘1’.

def hammingWeight(n: int) -> int:
    count = 0
    while n:
        count += n & 1
        n >>= 1
    return count

The time complexity of this approach is (O(1)) because the maximum number of bits to check is constant (32 bits for a standard unsigned integer in most programming environments).
The space complexity is (O(1)) as well, since we are using a constant amount of space irrespective of the input size.

count is initialized to 0 to keep track of the number of ‘1’ bits.
In the while loop:
- n & 1 checks if the least significant bit of n is ‘1’ (this is the bitwise AND operation).
- If it is ‘1’, we increment count.
- n >>= 1 shifts the bits of n to the right by 1, effectively removing the least significant bit.
The loop continues until all bits of n have been processed (i.e., n becomes 0).
Finally, we return the count of ‘1’s.

Would you like to proceed with this solution or do you have any additional requirements to consider?