I created a video editorial talking about how to use Atcoder Library's Segment Tree to optimize CF2019D: Speedbreaker
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Codeforces (c) Copyright 2010-2024 Михаил Мирзаянов
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Время на сервере: 22.11.2024 06:51:30 (k2).
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Very hard problems
I dont get it, D was extremely simple. You just have to track the first and last occursnce of each character, and then keep intersecting the segments.
A 20 line implementation would reach $$$O(n)$$$ without segment trees on this problem.
Yes, I agree Segment Tree might be an overkill for this problem. However, I arrived at the segtree solution without a lot of efforts, hence wanted to share an alternate solution from the editorial.
Also, looking at submission count of Problem C (6529) vs Problem D (1373), a lot of people did not submit the overkill segtree solution, possibly because they were not aware of such data structures or thought process of reducing the problem to a standard domain, hence the video.
Yes it's always useful to learn different ways to solve a problem.
Can you please explain your code and thought process of this problem ?