[Solved] Identify the bug in the following code that attempts to count the number of 1 bits in a signed 32-bit integer: def hammingWeight(n: int) -> int: count = 0 while n != 0:... | Bit Manipulation

Bit Manipulation - Number of 1 Bits (Hamming Weight)

Identify the bug in the following code that attempts to count the number of 1 bits in a signed 32-bit integer:

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

AThe loop condition 'while n != 0' causes infinite loop for negative numbers due to sign extension.

BThe bitwise AND operation 'n & 1' is incorrect; it should be logical AND 'n && 1'.

CThe right shift operator 'n >>= 1' should be replaced with left shift to count bits correctly.

DThe initial count variable should be initialized to 1 instead of 0.

Step-by-Step Solution

Step 1: Understand signed right shift behavior
In Python, right shifting a negative number propagates the sign bit, so n never becomes zero.
Step 2: Analyze loop condition
Because n != 0 remains true for negative numbers, the loop never terminates, causing infinite loop.
Final Answer:
Option A -> Option A
Quick Check:
Signed right shift on negative numbers causes infinite loop [OK]

Quick Trick: Signed right shift on negatives causes infinite loop [OK]

Common Mistakes:

MISTAKES

Trap Explanation:

PITFALL

Logical AND looks like a syntax error but distracts; shift direction and count init are plausible but wrong.

Interviewer Note:

CONTEXT

Checks understanding of signed vs unsigned shifts and edge cases with negative inputs.

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

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More Bit Manipulation Quizzes

Identify the bug in the following code that attempts to count the number of 1 bits in a signed 32-bit integer: