useful interview data structures: heapq (intermediate) anthony explains

today I show another useful interview datastructure -- heapq! I show how to use this to build a priority queue
playlist: • anthony explains
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[@limxunyi1823]

Recently found your channel from looking for help for advent of code questions, really love the explainations and look forward to binge watching a lot of your videos in the future!

[@akshaymestry971]

I had to implement priority queue for processing videos at work, had used recipe by David Beazley from his Cookbook. The implementation was fine but explaining the heapq implementation to the colleagues during knowledge transference was a nightmare. Your explanation is easy to understand, will share this vid with peers.

[@anthonywritescode]

glad it helps!

[@LunaFlahy]

4:57 priorityqueue

[@cakeinsauce]

Has anyone asked about contextvars in python? Curious to see the usage of them

[@anthonywritescode]

I've had a few questions about contextvars and admittedly I haven't used them myself -- they're intended to be an asyncio aware thread local (so you'd really only use them if you've got global variables and need async / threadsafe access to them)

[@kurianbenoy2]

In interviews for what kind of questions is this data structure useful?

[@anthonywritescode]

many popular algorithms require a priority queue -- for example dijkstra's

[@muhammadsarimmehdi]

can you provide an example where heapq would be preferred over a standard list?

[@anthonywritescode]

I show one in the video? but also heapsort or other heap-related algorithms perform much better without needing to continually re-shift the list items

[@marsma18]

And what 8f we have some workload which can have same priority? Can you continue on that topic.

[@anthonywritescode]

if they have the same priority then it doesn't matter

[@marsma18]

@@anthonywritescode Like we have 4 task 2 with prio 1 and then 2 and 3. We cannot use heapq as i remember in easy way

[@anthonywritescode]

should work fine, no modifications from what I showed in the video

[@erwan5112]

So, heapq or queue.PriorityQueue?

[@anthonywritescode]

good question, so the structures in `queue` are multiprocessing synchronized queues which are generally not what you want if you're just doing in-process work (they'll waste a lot of time locking / unlocking and setting up shared memory)