Codeforces Round 199 (Div. 2)
E
Xenia and Tree
Codeforces
2400
原题
← D→
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Xenia the programmer has a tree consisting of $*n*$ nodes. We will consider the tree nodes indexed from 1 to $*n*$. We will also consider the first node to be initially painted red, and the other nodes — to be painted blue.

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The distance between two tree nodes $*v*$ and $*u*$ is the number of edges in the shortest path between $*v*$ and $*u*$.

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Xenia needs to learn how to quickly execute queries of two types:

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  1. paint a specified blue node in red;
  2. calculate which red node is the closest to the given one and print the shortest distance to the closest red node.
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Your task is to write a program which will execute the described queries.

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Input

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The first line contains two integers $*n*$ and $*m*$ $(2 ≤ *n* ≤ 10^{5}, 1 ≤ *m* ≤ 10^{5})$ — the number of nodes in the tree and the number of queries. Next $*n* - 1$ lines contain the tree edges, the $*i*$-th line contains a pair of integers $*a*_{*i*}, *b*_{*i*}$ $(1 ≤ *a*_{*i*}, *b*_{*i*} ≤ *n*, *a*_{*i*} ≠ *b*_{*i*})$ — an edge of the tree.

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Next $*m*$ lines contain queries. Each query is specified as a pair of integers $*t*_{*i*}, *v*_{*i*}$ $(1 ≤ *t*_{*i*} ≤ 2, 1 ≤ *v*_{*i*} ≤ *n*)$. If $*t*_{*i*} = 1$, then as a reply to the query we need to paint a blue node $*v*_{*i*}$ in red. If $*t*_{*i*} = 2$, then we should reply to the query by printing the shortest distance from some red node to node $*v*_{*i*}$.

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It is guaranteed that the given graph is a tree and that all queries are correct.

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Output

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For each second type query print the reply in a single line.

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样例

Input #1
5 4
1 2
2 3
2 4
4 5
2 1
2 5
1 2
2 5
Output #1
0
3
2
InputCopy OutputCopy
题目信息
题号
342E
时间限制
5 s
内存限制
256 MB
标签
数据结构
分治
树

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。