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Which of the following modifications to the DP with bitmask tabulation approach correctly adapts to this change?

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Dynamic Programming: Knapsack - Partition to K Equal Sum Subsets
Suppose the problem is modified so that each element in the array can be used multiple times (unlimited reuse) to form k equal sum subsets. Which of the following modifications to the DP with bitmask tabulation approach correctly adapts to this change?
AUse backtracking with memoization on subsets but do not use bitmasking since reuse breaks subset uniqueness
BKeep the same bitmask DP but allow setting dp[next_mask] multiple times without restriction
CReplace bitmask DP with a classic unbounded knapsack DP that tracks sums without bitmasking
DModify the bitmask DP to reset dp states after each full subset sum is reached to allow reuse
Step-by-Step Solution
  1. Step 1: Understand reuse impact

    Allowing unlimited reuse breaks the uniqueness assumption of subsets represented by bitmasks.
  2. Step 2: Identify suitable DP approach

    Classic unbounded knapsack DP tracks sums without bitmasking, correctly handling reuse.
  3. Step 3: Evaluate other options

    Bitmask DP relies on unique element usage; modifying it without removing bitmasking leads to incorrect states.
  4. Final Answer:

    Option C -> Option C
  5. Quick Check:

    Unbounded knapsack DP handles reuse correctly [OK]
Quick Trick: Bitmask DP assumes unique usage; reuse needs unbounded knapsack DP [OK]
Common Mistakes:
MISTAKES
  • Trying to reuse bitmask DP without removing uniqueness assumption
  • Ignoring that reuse breaks subset partitioning logic
Trap Explanation:
PITFALL
  • Bitmask DP looks reusable but fails when elements can be reused multiple times.
Interviewer Note:
CONTEXT
  • Tests if candidate understands assumptions behind bitmask DP and can adapt to problem variants.
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