Answer:
is an undirected graph that consists of
nodes and
)
edges suchConstraints
2
≤
<
1
0
5
1
≤
2
≤
1
≤
[
]
≤
1
0
5
1
≤
edges
[
]
[
]
≤
Sample testcases explanation
that there is exactly one path between each pair of nodes. A walk is a traversal
in the graph, which can be expressed as a sequence of nodes. Nodes and
edges can be repeated in the walk. Thus, we can say that a walk is a path that
allows you to repeat nodes and edges.
You are given a tree of
nodes. However, each node has a restriction that
allowsionte
to be visited at most
[
i
]
times.
Your task is to find the length of the longest walk that starts in node S and
ends in
Since the answer might be large, return it modulo
1
0
9
°
+
7
.
Input Format
The first line contains an integer,
,
denoting the number of nodes.
The next dine contains an integer, S
,
denoting the node that you should start
and end the walk in
Each line
of the
subsequent lines
(
where
1
≤
≤
)
contains an integer
describing Ais
Each line iof the
-
1
subsequent lines
(
where
0
≤
Please provide optimised code