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Robot on tree - MarisaOJ: Marisa Online Judge

Robot on tree

Time limit: 1000 ms
Memory limit: 256 MB
You are given a tree of $n$ vertices. You have a robot. You can place it at a vertex $u$ on the tree and order it to move to $v$ using the simple path between 2 vertices. Moving from one vertex to another costs $1$ energy. When the robot runs out of energy, it stops. There are $q$ queries, each of the form $(u, v, w)$, the robot starts at $u$ and moves to $v$ with $w$ energy initially. Where will it stop? ### Input - The first line contain 2 integers $n, q$. - The next $n - 1$ lines, each line contains 2 integers $u, v$, there is an edge between $u$ and $v$. - The next $q$ lines, each line contains 3 integers $u, v, w$, an query. ### Output - Print $q$ integers, the answers to $q$ queries. ### Constraints - $1 \le n, q \le 10^5$. - $1 \le u, v, w \le n$. ### Example Input: ``` 7 3 1 2 1 3 2 4 2 5 3 6 3 7 1 4 1 5 6 2 6 5 3 ``` Output: ``` 2 1 2 ```
Lowest common ancestor (LCA)
LCA
Distance query
Robot on tree
Heaviest edge
Equal path
Triplet
Path update
Second best minimum spanning tree
Oggy and the cockroaches
Topic
Graph
Tree
Rating 1400
Source Codeforces
Solution (0) Solution