Bit Manipulation - Gray Code
Given the following Python code to generate Gray code sequence, what is the output of
grayCode(2)?Given the following Python code to generate Gray code sequence, what is the output of grayCode(2)?
easy🧾 Code Trace Q12 of Q15
Step-by-Step Solution
Solution:
Step 1: Compute values for i in range(4)
For i=0: 0 ^ (0>>1)=0; i=1: 1 ^ (0)=1; i=2: 2 ^ (1)=2^1=3; i=3: 3 ^ (1)=3^1=2Step 2: Collect results in list
The sequence is [0, 1, 3, 2], which matches the Gray code property.Final Answer:
Option C -> Option CQuick Check:
Manual XOR calculation confirms the sequence [0,1,3,2] [OK]
Quick Trick: XOR with right-shifted index generates Gray code directly [OK]
Common Mistakes:
MISTAKES- Confusing the order of XOR and shift
- Off-by-one errors in range leading to missing or extra elements
- Misinterpreting the output as binary numbers instead of integers
Trap Explanation:
PITFALL- Candidates often confuse the bitwise operations or the range boundaries, leading to incorrect sequences.
Interviewer Note:
CONTEXT- Checks if candidate can mentally execute bitwise code and understand Gray code generation.
Master "Gray Code" in Bit Manipulation
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