Subsets & Combinations - Combination Sum II (No Reuse, Duplicates)
What is the output of the optimal backtracking solution for Combination Sum II when candidates = [5] and target = 0?
What is the output of the optimal backtracking solution for Combination Sum II when candidates = [5] and target = 0?
medium🧾 Code Trace Q4 of Q15
Step-by-Step Solution
Solution:
Step 1: Check base case for target=0
When target is zero at start, the empty combination is a valid solution and appended.Step 2: Confirm no further recursion
No candidates are chosen since target is zero, so result is [[]].Final Answer:
Option A -> Option AQuick Check:
Empty subset sums to zero [OK]
Quick Trick: Target zero means empty subset is valid [OK]
Common Mistakes:
MISTAKES- Returning empty list instead of list with empty list
- Ignoring base case for zero target
Trap Explanation:
PITFALL- Candidates often forget that target=0 means a valid combination (empty) must be returned.
Interviewer Note:
CONTEXT- Tests understanding of base cases and edge inputs in backtracking.
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