broly_1033's blog

By broly_1033, history, 7 months ago, In English

Hi everyone, I was studying how to solve query problems on trees using Euler Tour. I was wondering how to solve path query problems on trees. We can solve problems which can be solved by maintaining a prefix array (for e.g. sum of nodes in path from a to b), but how to solve say, node with maximum value in path from a to b. Can anyone guide me on this?
More specifically, sum(a, b) = sum(root, a) + sum(root, b) — 2*sum(root, lca(a, b)) + val(lca). I was using this to solve these problems using Euler Tour. But I cannot find maximum using this (CSES Path Queries 2).
Q1. Can we apply segment trees on Euler Tour array? Q2. How to solve problems like CSES Path Queries 2?

 
 
 
 
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7 months ago, # |
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Yah you need to use heavy light decomposition, which basically uses segment tree.

I hope this helps

https://codeforces.cc/blog/entry/81317

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    7 months ago, # ^ |
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    I have heard of HLD but couldn't seem to grasp it. Thanks, is there any other method though?

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      7 months ago, # ^ |
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      It is a fairly high level concept, if I was you I would focus on easier topics first.

      No I don't think there's any other way of solving this problem.