[Solved] Consider the following Python function intended to count the number of set bits in a signed 32-bit integer:def countSetBits(n: int) -> int: count = 0 while n != 0:... | Bit Manipulation

Bit Manipulation - Number of 1 Bits (Hamming Weight)

Consider the following Python function intended to count the number of set bits in a signed 32-bit integer:

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

What is the main issue with this implementation when n is negative?

AThe loop condition should be while n > 0 instead of n != 0

BThe bitwise AND operation is invalid for negative numbers

CThe function does not initialize count correctly

DRight shift on negative numbers performs arithmetic shift, causing an infinite loop

Step-by-Step Solution

Solution:

Step 1: Understand right shift on negative integers
In Python, right shifting a negative integer performs an arithmetic shift, preserving the sign bit.
Step 2: Effect on loop condition
Because the sign bit remains 1, n never becomes zero, causing an infinite loop.
Final Answer:
Option D -> Option D
Quick Check:
Negative n right shift keeps sign bit set, loop never ends [OK]

Quick Trick: Right shift on negative int is arithmetic, beware infinite loops [OK]

Common Mistakes:

MISTAKES

Trap Explanation:

PITFALL

Option D looks plausible but changing loop condition doesn't fix infinite loop caused by arithmetic shift.

Interviewer Note:

CONTEXT

Master "Number of 1 Bits (Hamming Weight)" in Bit Manipulation

3 interactive learning modes - each teaches the same concept differently

More Bit Manipulation Quizzes

Consider the following Python function intended to count the number of set bits in a signed 32-bit integer: