Bit Manipulation - Single Number III (Two Singles)
What is the output of the XOR and partition code when the input is [0, 0, -1, -2]?
What is the output of the XOR and partition code when the input is [0, 0, -1, -2]?
medium🧾 Code Trace Q4 of Q15
Step-by-Step Solution
Solution:
Step 1: XOR all elements
0 ^ 0 ^ -1 ^ -2 = (-1) ^ (-2) = 1 (binary 1)Step 2: Find rightmost set bit
1 & (-1) = 1 (binary 1)Step 3: Partition and XOR groups
Group with bit set: -1; Group without bit set: 0, 0, -2 -> XOR = -2Final Answer:
Option B -> Option BQuick Check:
Output correctly identifies unique negatives [OK]
Quick Trick: Handle negative numbers carefully with two's complement [OK]
Common Mistakes:
MISTAKES- Misinterpreting negative bit operations
- Assuming set bit always positive
Trap Explanation:
PITFALL- Candidates often mishandle negative numbers in bitwise operations causing wrong partitioning.
Interviewer Note:
CONTEXT- Tests edge case handling of negative numbers in XOR partition.
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