Subsets & Combinations - Subsets
Given the following code snippet, what is the output when calling subsets([1, 2])?
Given the following code snippet, what is the output when calling subsets([1, 2])?
easy🧾 Code Trace Q3 of Q15
Step-by-Step Solution
Solution:
Step 1: Trace mask values from 0 to 3 for nums=[1,2]
mask=0 -> [], mask=1 -> [1], mask=2 -> [2], mask=3 -> [1,2]Step 2: Collect subsets in order of mask
Result is [[], [1], [2], [1, 2]]Final Answer:
Option B -> Option BQuick Check:
Bitmask enumeration includes empty subset first [OK]
Quick Trick: Bitmask 0 corresponds to empty subset [OK]
Common Mistakes:
MISTAKES- Forgetting empty subset at mask=0
- Misordering subsets
Trap Explanation:
PITFALL- Candidates often forget the empty subset or misorder subsets when tracing bitmask loops.
Interviewer Note:
CONTEXT- Tests ability to mentally execute bitmask subset generation
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