Greedy Algorithms - Task Scheduler (CPU Cooling)
Given the following code for the Task Scheduler, what is the returned value for
leastInterval(['A','A','B'], 2)?Given the following code for the Task Scheduler, what is the returned value for leastInterval(['A','A','B'], 2)?
easy🧾 Code Trace Q12 of Q15
Step-by-Step Solution
Step 1: Initialize frequencies and max-heap
Tasks: A(2), B(1). Max-heap: [-2, -1].Step 2: Simulate scheduling cycles
Cycle 1: pop -2 (A), decrement to -1 and store; pop -1 (B), decrement to 0 ignore; cycle=2, heap not empty -> time += n+1=3.
Cycle 2: pop -1 (A), decrement to 0 ignore; cycle=1, heap empty -> time += cycle=1.
Total time = 3 + 1 = 4.Final Answer:
Option D -> Option DQuick Check:
Manual simulation matches 4 units [OK]
Quick Trick: Count cycles and add idle if heap not empty [OK]
Common Mistakes:
MISTAKES- Off-by-one in cycle count
- Adding n+1 even when heap empty
- Ignoring decrement of counts
Trap Explanation:
PITFALL- Candidates often add full cooldown even when tasks finish early, overestimating time.
Interviewer Note:
CONTEXT- Tests ability to mentally execute heap-based greedy scheduling and track time correctly.
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