10054: ABC340 —— G - Leaf Color
[Creator : ]
Description
There is a tree $T$ with $N$ vertices numbered from $1$ to $N$. The $i$-th edge connects vertices $u_i$ and $v_i$. Additionally, vertex $i$ is painted with color $A_i$.
Find the number, modulo $998244353$, of (non-empty) subsets $S$ of the vertex set of $T$ that satisfy the following condition:
- The induced subgraph $G$ of $T$ by $S$ satisfies all of the following conditions:
- $G$ is a tree.
- All vertices with degree $1$ have the same color.
What is an induced subgraph? Let $S$ be a subset of the vertices of a graph $G$. The induced subgraph of $G$ by $S$ is a graph whose vertex set is $S$ and whose edge set consists of all edges in $G$ that have both endpoints in $S$.
Find the number, modulo $998244353$, of (non-empty) subsets $S$ of the vertex set of $T$ that satisfy the following condition:
- The induced subgraph $G$ of $T$ by $S$ satisfies all of the following conditions:
- $G$ is a tree.
- All vertices with degree $1$ have the same color.
What is an induced subgraph? Let $S$ be a subset of the vertices of a graph $G$. The induced subgraph of $G$ by $S$ is a graph whose vertex set is $S$ and whose edge set consists of all edges in $G$ that have both endpoints in $S$.
Input
The input is given from Standard Input in the following format:
```
$N$
$A_1$ $A_2$ $\dots$ $A_N$
$u_1$ $v_1$
$u_2$ $v_2$
$\vdots$
$u_{N-1}$ $v_{N-1}$
```
```
$N$
$A_1$ $A_2$ $\dots$ $A_N$
$u_1$ $v_1$
$u_2$ $v_2$
$\vdots$
$u_{N-1}$ $v_{N-1}$
```
Output
Print the number, modulo $998244353$, of (non-empty) subsets $S$ of the vertex set of $T$ that satisfy the condition in the problem statement.
Constraints
- $1 \leq N \leq 2 \times 10^5$
- $1 \leq A_i \leq N$
- $1 \leq u_i \lt v_i \leq N$
- The graph given in the input is a tree.
- All input values are integers.
- $1 \leq A_i \leq N$
- $1 \leq u_i \lt v_i \leq N$
- The graph given in the input is a tree.
- All input values are integers.
Sample 1 Input
3
1 2 1
1 2
2 3
Sample 1 Output
4
The following four sets of vertices satisfy the condition.
- {1}
- {1,2,3}
- {2}
- {3}
Sample 2 Input
5
2 2 1 1 1
2 5
3 4
1 3
1 5
Sample 2 Output
9
Sample 3 Input
15
5 3 5 1 1 4 4 4 2 5 5 4 4 2 5
3 13
4 10
7 11
8 9
2 10
2 14
5 11
5 6
6 13
12 13
9 14
9 13
1 13
1 15
Sample 3 Output
48