Bit Manipulation - Subsets Using Bitmask
Given the following partial output of subsets generated from an unknown input array:
[[], [2], [3], [2, 3]]
Which of the following could be the original input array?
Given the following partial output of subsets generated from an unknown input array: [[], [2], [3], [2, 3]] Which of the following could be the original input array?
hard🔄 Reverse Engineer Q9 of Q15
Step-by-Step Solution
Solution:
Step 1: Analyze subsets
Subsets include empty, single elements 2 and 3, and their combination [2,3].Step 2: Match subsets to input
Only input [2,3] produces exactly these subsets; others include 1 or 4 which are missing.Final Answer:
Option C -> Option CQuick Check:
Subsets match input elements 2 and 3 exactly [OK]
Quick Trick: Subsets must match all elements and combinations [OK]
Common Mistakes:
MISTAKES- Ignoring missing elements in subsets
- Assuming subsets are incomplete
Trap Explanation:
PITFALL- Candidates may pick inputs with extra elements not reflected in subsets.
Interviewer Note:
CONTEXT- Tests candidate's ability to reason backwards from output to input.
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