Bit Manipulation - Single Number II (Three Copies)
Given the final values of ones=5 and twos=0 after processing an input array with the bitwise FSM, which of the following input arrays could produce this state?
Given the final values of ones=5 and twos=0 after processing an input array with the bitwise FSM, which of the following input arrays could produce this state?
hard🔄 Reverse Engineer Q9 of Q15
Step-by-Step Solution
Solution:
Step 1: Understand FSM final state meaning
ones=5 means unique element is 5; twos=0 means no bits are in the 'twice seen' state.Step 2: Identify input matching unique element 5 appearing once
[5, 5, 5, 2] has 2 appearing thrice and 5 appearing once, matching FSM logic.Final Answer:
Option A -> Option AQuick Check:
Only option with 5 once and 2 thrice fits FSM final state [OK]
Quick Trick: ones holds unique element after processing [OK]
Common Mistakes:
MISTAKES- Confusing which element is unique
- Ignoring twos state meaning
Trap Explanation:
PITFALL- Candidates often misinterpret FSM states and final values, guessing wrong input.
Interviewer Note:
CONTEXT- Tests deep understanding of FSM state meaning and reverse reasoning.
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