877E - Danil and a Part-time Job is an interesting problem that requires queries and updates on subtrees of a tree. It is a great problem to learn a variation of traditional segment trees.
I created a video tutorial explaining the problem. I explained how to order the nodes so that it's possible to use a segment tree and how to do toggle updates.
Here is my YouTube channel with all the video tutorials.
Please try to post videos frequently :)
I am busy at the moment, but I will try to post the next one as soon as possible, probably in in two weeks (I know that's late but after that, I'll try to post every week).
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amazing explanation .. make more such videos . : )