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What is the output of the following code when the input is 11?

easy🧾 Code Trace Q12 of Q15
Bit Manipulation - Number of 1 Bits (Hamming Weight)
What is the output of the following code when the input is 11? 
def hammingWeight(n: int) -> int:
    return bin(n).count('1')

print(hammingWeight(11))
A2
B4
C3
D1
Step-by-Step Solution

  1. Step 1: Convert 11 to binary

    11 in binary is 1011.

  2. Step 2: Count '1's in '1011'

    There are three '1's in the string.

  3. Final Answer:

    Option C -> Option C

  4. Quick Check:

    bin(11) = '0b1011', count('1') = 3 [OK]
Quick Trick: Count '1's in binary string representation [OK]
Common Mistakes:
MISTAKES
  • Counting bits incorrectly
  • Confusing decimal and binary digits
Trap Explanation:
PITFALL
  • Off-by-one errors in counting bits or misreading binary string length.
Interviewer Note:
CONTEXT
  • Checks ability to trace built-in function usage and understand binary representation.
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