Bit Manipulation - Subsets Using Bitmask
To generate all subsets where elements can be chosen multiple times (multisets), which change to the backtracking approach is required?
To generate all subsets where elements can be chosen multiple times (multisets), which change to the backtracking approach is required?
hard🔁 Follow Up Q10 of Q15
Step-by-Step Solution
Solution:
Step 1: Understand multiset subsets
Elements can be repeated unlimited times in subsets.Step 2: Modify recursion
Instead of moving to next index, allow recursion to reuse current index to pick element multiple times.Step 3: Avoid skipping elements
Do not increment index after picking element to allow repetition.Final Answer:
Option D -> Option DQuick Check:
Reusing index enables unlimited element repetition [OK]
Quick Trick: Reuse current index in recursion for unlimited repeats [OK]
Common Mistakes:
MISTAKES- Using bitmask enumeration which can't handle unlimited repeats easily
- Sorting and skipping duplicates which is for unique subsets
- Stopping recursion early which limits subset size
Trap Explanation:
PITFALL- Skipping index increment is necessary to allow repeated elements; otherwise subsets miss repeats.
Interviewer Note:
CONTEXT- Tests understanding of adapting subset generation for multisets with unlimited element reuse.
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