等度数删除AI (CI翻译)
Problem Statement
题目描述
AI (CI翻译)You are given a tree $G$ with $N$ vertices and $N-1$ edges.
The vertices are numbered $1$ to $N$, and the edges are numbered $1$ to $N-1$. Edge $i$ connects vertices $u_i$ and $v_i$.
给定一棵有 $N$ 个顶点和 $N-1$ 条边的树 $G$。
顶点编号为 $1$ 到 $N$,边编号为 $1$ 到 $N-1$。边 $i$ 连接顶点 $u_i$ 和 $v_i$。AI (CI翻译)
A tree $H$ is called special if it is possible to delete all edges of $H$ by performing the following operation zero or more times.
如果可以通过零次或多次执行以下操作删除树 $H$ 的所有边,则称树 $H$ 是特殊的。AI (CI翻译)
- Choose an edge connecting two vertices whose current degrees are equal, and delete it.
- 选择一条连接当前度数相同的两个顶点的边,并将其删除。
Find the number of special subtrees of $G$, modulo $998244353$.
求 $G$ 的特殊子树数量,答案对 $998244353$ 取模。AI (CI翻译)
Solve $T$ test cases for each input.
对于每组输入,求解 $T$ 组测试用例。AI (CI翻译)
What is a subtree? A subtree of a tree $G$ is a connected subgraph of $G$.
什么是子树?树 $G$ 的子树是 $G$ 的一个连通子图。AI (CI翻译)
Constraints
约束条件
AI (CI翻译)$1 \leq T \leq 10^5$$2 \leq N \leq 3 \times 10^5$- The sum of
$N$over all test cases is at most$3 \times 10^5$. $1 \leq u_i \lt v_i \leq N$- The given graph
$G$is a tree. - All input values are integers.
$1 \leq T \leq 10^5$$2 \leq N \leq 3 \times 10^5$- 所有测试用例的
$N$之和不超过$3 \times 10^5$。 $1 \leq u_i \lt v_i \leq N$- 给定的图
$G$是一棵树。 - 所有输入值均为整数。
Input
输入格式
AI (CI翻译)The input is given from Standard Input in the following format:
输入通过标准输入给出,格式如下:AI (CI翻译)
T
\mathrm{case}_1
\mathrm{case}_2
\vdots
\mathrm{case}_T
T
\mathrm{case}_1
\mathrm{case}_2
\vdots
\mathrm{case}_TAI (CI翻译)
Each test case $\mathrm{case}_t$ is given in the following format:
每组测试用例 $\mathrm{case}_t$ 的格式如下:AI (CI翻译)
N
u_1 v_1
u_2 v_2
\vdots
u_{N-1} v_{N-1}
N
u_1 v_1
u_2 v_2
\vdots
u_{N-1} v_{N-1}AI (CI翻译)
Output
输出格式
AI (CI翻译)Print $T$ lines in total. The $t$-th line should contain the answer for the $t$-th test case.
总共输出 $T$ 行。第 $t$ 行应包含第 $t$ 组测试用例的答案。AI (CI翻译)
样例
3
6
1 3
2 3
3 4
4 5
4 6
10
2 6
4 5
3 9
6 8
3 5
6 10
3 7
1 10
2 5
2
1 2
15
35
3
题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(gpt-6.1-sol),如有出入请以原文为准。