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Given an integer array that may contain duplicates, which method ensures all unique subsets are generated without repetition?

easy💻 Programming Q1 of Q15
Subsets & Combinations - Subsets II (With Duplicates)
Given an integer array that may contain duplicates, which method ensures all unique subsets are generated without repetition?
AGenerate all subsets without sorting and then filter duplicates at the end
BUse a hash set to store subsets generated from a brute force approach
CSort the array and use backtracking with a skip condition for duplicates
DUse a greedy approach to pick elements only once
Step-by-Step Solution
Solution:

  1. Step 1: Sort the array to group duplicates

    Sorting groups duplicates together, making it easier to skip them during subset generation.

  2. Step 2: Use backtracking with a skip condition for duplicates

    When encountering duplicates at the same recursion depth, skip processing the same element to avoid duplicate subsets.

  3. Final Answer:

    Option C -> Option C

  4. Quick Check:

    Sorting combined with skipping duplicates during backtracking ensures unique subsets [OK]
Quick Trick: Sort and skip duplicates during backtracking [OK]
Common Mistakes:
MISTAKES
  • Not sorting before backtracking leads to duplicate subsets
  • Filtering duplicates after generating all subsets is inefficient
  • Using greedy approach misses subsets
Trap Explanation:
PITFALL
  • Filtering duplicates after generation looks simpler but is inefficient and error-prone
Interviewer Note:
CONTEXT
  • Tests understanding of handling duplicates in subset generation
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