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If the Ones and Zeroes problem is changed so that each binary string can be selected unlimited times, which modification to the bottom-up dynamic programming solution is required to correctly solve this variant?

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Dynamic Programming: Knapsack - Ones and Zeroes (2D Knapsack)
If the Ones and Zeroes problem is changed so that each binary string can be selected unlimited times, which modification to the bottom-up dynamic programming solution is required to correctly solve this variant?
AUpdate the DP table in increasing order of zeros and ones to allow multiple counts
BUse a top-down memoization approach instead of bottom-up
CSort strings by length before processing
DInitialize the DP table with negative infinity values
Step-by-Step Solution
Solution:
  1. Step 1: Understand the change

    Allowing unlimited usage of each string converts the problem to an unbounded knapsack variant.
  2. Step 2: Identify DP update order

    For unbounded knapsack, the DP table must be updated in increasing order of resource constraints to reuse items multiple times.
  3. Step 3: Apply correct DP iteration

    Iterate zeros from 0 to m and ones from 0 to n, updating dp[i][j] by considering current string multiple times.
  4. Final Answer:

    Option A -> Option A
  5. Quick Check:

    Unbounded knapsack requires forward DP iteration [OK]
Quick Trick: Unbounded knapsack needs forward DP iteration [OK]
Common Mistakes:
MISTAKES
  • Using backward iteration which suits 0/1 knapsack only
  • Switching to top-down unnecessarily
  • Incorrect DP initialization causing wrong results
Trap Explanation:
PITFALL
  • Backward iteration is correct for 0/1 knapsack but fails for unbounded usage.
Interviewer Note:
CONTEXT
  • Tests knowledge of adapting DP solutions for unbounded knapsack variants.
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