621. Task Scheduler

• Use heap and queue to track item and idle time
• log(26)

class Solution:
    def leastInterval(self, tasks: List[str], n: int) -> int:
        counts = Counter(tasks)
        maxHeap = [-cnt for cnt in counts.values()]
        heapq.heapify(maxHeap)

        q = deque()
        time = 0

        while maxHeap or q:
            time += 1

            if maxHeap:
                val = heapq.heappop(maxHeap) + 1
                if val:
                    q.append([val, n + time])

            if q and q[0][1] == time:
                heapq.heappush(maxHeap, q.popleft()[0])


        return time