Bit Manipulation - Single Number II (Three Copies)
Suppose the problem changes: every element appears k times except one unique element appearing once, where k is unknown and can vary. Which approach best adapts to this variant?
Suppose the problem changes: every element appears k times except one unique element appearing once, where k is unknown and can vary. Which approach best adapts to this variant?
hard🎤 Interviewer Follow-up Q10 of Q15
Step-by-Step Solution
Solution:
Step 1: Analyze problem variant
Unknown k means fixed modulo or FSM approaches for k=3 won't work without modification.Step 2: Identify adaptable approach
Hash map counting occurrences works regardless of k, though uses extra space.Step 3: Evaluate other options
Sorting is O(n log n) and less efficient; bit counting and FSM require known k.Final Answer:
Option D -> Option DQuick Check:
Hash map works for unknown k variants [OK]
Quick Trick: Unknown k breaks fixed modulo FSM; hash map is flexible [OK]
Common Mistakes:
MISTAKES- Assuming FSM works for any k
- Ignoring hash map as flexible solution
Trap Explanation:
PITFALL- Candidates often try to apply fixed k solutions to unknown k problems incorrectly.
Interviewer Note:
CONTEXT- Tests adaptability and understanding of approach limitations.
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