Puzzle 4 A Task to Do

Python Brain Teasers — by Miki Tebeka (13 / 40)

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tasks.py

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

Guess the Output

IMPORTANT

Try to guess what the output is before moving to the next page.

This code will raise a TypeError exception.

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 (e.g., tasks[0]) is always the smallest.

To compare items in the heap, heapq uses the comparison defined in the object’s type (using the < operator, which maps to the specific type’s __lt__ special…