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Problem

Task Scheduler

LeetCode #621Medium
Most-frequent-first · max-heap vs. the frame formula

Given task labels and a cooldown n, the same task must run at least n intervals apart. Return the minimum number of intervals (including idles) needed to finish every task.

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schedule
Greedy · most-frequent-first (max-heap)
▸
1count tasks;  heap = max-heap by remaining count
2time = 0
3while tasks remain:
4    run up to n+1 distinct tasks, highest count first
5        (decrement; re-add to heap if count > 0)
6    if a slot has no available task → idle
7    advance one cooldown frame
8return time
state
  • n (cooldown)2
  • A3
  • B3

line 1Schedule all 6 tasks so equal labels stay ≥ n = 2 intervals apart, with the FEWEST intervals (idles count). The bottleneck is the MOST FREQUENT task — give it priority and pack the gaps around it.