[Solved] Suppose you want to generate all permutations of n elements but now elements can be reused any number of times (i.e.... Which modification to the bitmask DP approach is correct? | Bit Manipulation

Bit Manipulation - Generate All Permutations Using Bitmask DP

Suppose you want to generate all permutations of n elements but now elements can be reused any number of times (i.e., permutations with repetition). Which modification to the bitmask DP approach is correct?

AUse iterative DP over sequence length without bitmask since visited state is irrelevant

BKeep bitmask DP but allow setting bits multiple times to reuse elements

CRemove bitmask tracking and use simple recursion with repeated choices allowed

DUse bitmask DP but reset dp states after each iteration to allow reuse

Step-by-Step Solution

Step 1: Understand reuse means no visited tracking needed
Since elements can be reused, the visited bitmask is no longer meaningful.
Step 2: Use DP over sequence length only
Iterative DP over length with choices from all elements at each step correctly generates permutations with repetition.
Final Answer:
Option A -> Option A
Quick Check:
Bitmask DP is unnecessary when elements can be reused [OK]

Quick Trick: Reuse means no visited bitmask needed; track length only [OK]

Common Mistakes:

MISTAKES

Trying to reuse bitmask DP without modification
Allowing bits to be set multiple times breaks bitmask logic

Trap Explanation:

PITFALL

Naively reusing bitmask DP fails because bitmask states assume no reuse; resetting states or reusing bits is invalid.

Interviewer Note:

CONTEXT

Tests candidate's ability to adapt bitmask DP to problem variants with relaxed constraints.

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Which modification to the bitmask DP approach is correct?

Step 1: Understand reuse means no visited tracking needed

Step 2: Use DP over sequence length only

Final Answer:

Quick Check:

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