Subsets & Combinations - Subsets II (With Duplicates)
Which of the following problems CANNOT be solved efficiently using the Subsets II (With Duplicates) backtracking pattern?
Which of the following problems CANNOT be solved efficiently using the Subsets II (With Duplicates) backtracking pattern?
easy🔍 Pattern Recognition Q2 of Q15
Step-by-Step Solution
Solution:
Step 1: Analyze problem requirements
The Subsets II pattern handles unique subsets ignoring order, but problems involving unlimited reuse or fixed size subsets require different patterns.Step 2: Identify anti-pattern
Finding all unique combinations of coins to make a target sum with unlimited reuse involves unlimited reuse (combinations with repetition), which requires a different pattern (combination sum), not Subsets II. Returning all subsets of fixed size k from an array with duplicates is a different pattern (combinations of size k). Generating all unique subsets where order of elements does not matter is solvable by Subsets II pattern.Final Answer:
Option A -> Option AQuick Check:
Only the unlimited reuse problem is not solvable by Subsets II pattern [OK]
Quick Trick: Unlimited reuse or fixed size subsets need different patterns [OK]
Common Mistakes:
MISTAKES- Confusing unlimited reuse with subsets without repetition
- Thinking fixed size subsets are solved by Subsets II pattern
Trap Explanation:
PITFALL- Candidates often think all subset-related problems fit Subsets II pattern, missing nuances like unlimited reuse or fixed size constraints.
Interviewer Note:
CONTEXT- Tests candidate's ability to distinguish closely related but different subset problems.
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