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If the problem changes to generating all subsets of an array where elements can be repeated unlimited times (multisets), which approach must be modified or replaced?

hard🎤 Interviewer Follow-up Q10 of Q15

Subsets & Combinations - Subsets Using Bitmask

If the problem changes to generating all subsets of an array where elements can be repeated unlimited times (multisets), which approach must be modified or replaced?

ABitmask enumeration cannot represent multisets and must be replaced

BBacktracking must be replaced with dynamic programming

CIterative subset construction without modification works as is

DNo change needed; all approaches handle multisets naturally

Step-by-Step Solution

Solution:

Step 1: Understand multisets
Multisets allow repeated elements; subsets can include duplicates multiple times.
Step 2: Evaluate approaches
Bitmask enumeration cannot represent repeated elements since bits represent presence/absence only.
Step 3: Identify correct approach
Backtracking can be adapted to allow repeated inclusion; iterative approach must be modified to handle repeats.
Final Answer:
Option A -> Option A
Quick Check:
Bitmask enumeration fails for multisets [OK]

Quick Trick: Bitmask only for distinct elements [OK]

Common Mistakes:

MISTAKES

Assuming bitmask works for multisets
Ignoring need for modified recursion

Trap Explanation:

PITFALL

Candidates often think bitmask can handle repeats, but it cannot encode counts.

Interviewer Note:

CONTEXT

Tests ability to adapt subset generation to problem variants.

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