Bit Manipulation - Single Number (XOR Self-Cancellation)
If the input array contains multiple elements that appear only once, while all others appear twice, which approach is best to find all unique elements?
If the input array contains multiple elements that appear only once, while all others appear twice, which approach is best to find all unique elements?
hard🎤 Interviewer Follow-up Q10 of Q15
Step-by-Step Solution
Solution:
Step 1: Understand XOR limitation
Simple XOR finds only one unique element; multiple uniques require advanced bitmasking or other methods.Step 2: Use hash map for multiple uniques
Hash maps count occurrences and collect all unique elements efficiently.Step 3: Compare with other approaches
Sorting is slower; XOR with bitmasking is complex and less straightforward than hash maps for multiple uniques.Final Answer:
Option C -> Option CQuick Check:
Hash map is practical and clear for multiple unique elements [OK]
Quick Trick: Hash maps handle multiple uniques clearly [OK]
Common Mistakes:
MISTAKES- Trying simple XOR for multiple uniques
- Ignoring space/time trade-offs
Trap Explanation:
PITFALL- Candidates often try naive XOR or bitmasking without hash maps for multiple uniques.
Interviewer Note:
CONTEXT- Tests practical approach selection for multiple unique elements.
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