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Puzzle 4: Explanation

Learn how Python's built-in heapq module manages min-heaps using lexicographical order for tuple comparisons. This lesson helps you understand priority queue operations, tuple ordering, and how data types impact heap behavior in Python puzzles.

Try it yourself

Execute the code below to verify the result:

Python 3.8
from heapq import heappush, heappop
tasks = []
heappush(tasks, (30, 'work out'))
heappush(tasks, (10, 'wake up'))
heappush(tasks, (20, 0xCAFFE))
heappush(tasks, (20, 'feed cat'))
heappush(tasks, (40, 'write book'))
while tasks:
_, payload = heappop(tasks)
print(payload)

Explanation

The built-in heapq module implements min-heap over lists. It’s common to use a heap for a priority queue. Pushing and deleting from the heap are log(N) operations, and the first item in the heap (tasks[0]) is always the ...