[Solved] Examine the following buggy code snippet for partitioning an array into k equal sum subsets using backtracking... Which line contains the subtle bug that can cause incorrect results or inefficiency? | Subsets & Combinations

Subsets & Combinations - Partition to K Equal Sum Subsets

Examine the following buggy code snippet for partitioning an array into k equal sum subsets using backtracking with bitmask memoization. Which line contains the subtle bug that can cause incorrect results or inefficiency?

ALine 2: missing check if total is divisible by k

BLine 6: sorting nums in descending order

CLine 14: memoizing result after recursive call

DLine 18: checking if element is unused and fits in current subset

Step-by-Step Solution

Step 1: Identify missing early pruning
Line 2 calculates total but does not check if total % k != 0, which is critical to avoid futile search.
Step 2: Verify other lines
Sorting descending (line 6) is correct for pruning; memoization (line 14) and usage check (line 18) are correct.
Final Answer:
Option A -> Option A
Quick Check:
Without divisibility check, algorithm wastes time exploring impossible partitions [OK]

Quick Trick: Always check divisibility before backtracking [OK]

Common Mistakes:

MISTAKES

Forgetting early divisibility check
Misplacing memoization

Trap Explanation:

PITFALL

Missing divisibility check looks harmless but causes exponential blowup

Interviewer Note:

CONTEXT

Tests attention to critical pruning conditions in backtracking

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More Subsets & Combinations Quizzes

Which line contains the subtle bug that can cause incorrect results or inefficiency?

Step 1: Identify missing early pruning

Step 2: Verify other lines

Final Answer:

Quick Check:

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