Subsets & Combinations - Combination Sum (Reuse Allowed)
Given a list of unique positive integers and a target sum, which technique is most suitable to find all combinations where numbers can be reused unlimited times to reach the target?
Given a list of unique positive integers and a target sum, which technique is most suitable to find all combinations where numbers can be reused unlimited times to reach the target?
easy💻 Programming Q1 of Q15
Step-by-Step Solution
Solution:
Step 1: Identify the problem type
This is a combination problem with reuse allowed, requiring exploration of multiple paths.Step 2: Choose algorithmic pattern
Backtracking with recursion and pruning efficiently explores all valid combinations without duplicates.Final Answer:
Option C -> Option CQuick Check:
Backtracking handles reuse and pruning avoids unnecessary paths [OK]
Quick Trick: Use backtracking for combinations with unlimited reuse [OK]
Common Mistakes:
MISTAKES- Assuming greedy approach works for all target sums
- Using DP without handling reuse properly
- Ignoring pruning leading to timeouts
Trap Explanation:
PITFALL- Greedy and DP without recursion do not handle reuse and all combinations correctly.
Interviewer Note:
CONTEXT- Tests understanding of appropriate algorithmic patterns for combination problems with reuse.
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