Bit Manipulation - Single Number (XOR Self-Cancellation)
Given the XOR accumulator value after processing an array is 6, and the array contains pairs of numbers except one unique number, which of the following could be the unique number?
Given the XOR accumulator value after processing an array is 6, and the array contains pairs of numbers except one unique number, which of the following could be the unique number?
hard🔄 Reverse Engineer Q9 of Q15
Step-by-Step Solution
Solution:
Step 1: Understand XOR accumulator meaning
The accumulator holds XOR of all elements, pairs cancel out, leaving unique number.Step 2: Unique number equals accumulator value
Therefore, unique number must be 6.Final Answer:
Option A -> Option AQuick Check:
Accumulator equals unique element [OK]
Quick Trick: XOR accumulator equals unique number [OK]
Common Mistakes:
MISTAKES- Assuming accumulator could be any number
- Confusing parity with value
Trap Explanation:
PITFALL- Candidates sometimes think accumulator is unrelated to unique number.
Interviewer Note:
CONTEXT- Tests reverse reasoning from output to input.
Master "Single Number (XOR Self-Cancellation)" in Bit Manipulation
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