#P1857G. Counting Graphs

    ID: 8609 Type: RemoteJudge 2000ms 256MiB Tried: 0 Accepted: 0 Difficulty: 7 Uploaded By: Tags>combinatoricsdivide and conquerdsugraphsgreedysortingstrees*2000

Counting Graphs

No submission language available for this problem.

Description

Given a tree consisting of nn vertices. A tree is a connected undirected graph without cycles. Each edge of the tree has its weight, wiw_i.

Your task is to count the number of different graphs that satisfy all four conditions:

  1. The graph does not have self-loops and multiple edges.
  2. The weights on the edges of the graph are integers and do not exceed SS.
  3. The graph has exactly one minimum spanning tree.
  4. The minimum spanning tree of the graph is the given tree.

Two graphs are considered different if their sets of edges are different, taking into account the weights of the edges.

The answer can be large, output it modulo 998244353998244353.

The first line contains an integer tt (1t1041\le t\le 10^4) — the number of test cases.

The first line of each test case contains two integers nn and SS (2n2105,1S1092 \le n \le 2 \cdot 10^5, 1\le S\le 10^9) — the number of vertices and the upper bound of the weights.

Then follow n1n-1 lines describing the tree, the ii-th line contains three integers uiu_i, viv_i, and wiw_i (1ui,vin,uivi,1wiS1\le u_i,v_i\le n, u_i \ne v_i, 1\le w_i\le S) — an edge in the tree with weight wiw_i.

It is guaranteed that the sum of nn for all tests does not exceed 21052\cdot 10^5.

For each test, output the number of different graphs that satisfy the conditions, modulo 998244353998244353.

Input

The first line contains an integer tt (1t1041\le t\le 10^4) — the number of test cases.

The first line of each test case contains two integers nn and SS (2n2105,1S1092 \le n \le 2 \cdot 10^5, 1\le S\le 10^9) — the number of vertices and the upper bound of the weights.

Then follow n1n-1 lines describing the tree, the ii-th line contains three integers uiu_i, viv_i, and wiw_i (1ui,vin,uivi,1wiS1\le u_i,v_i\le n, u_i \ne v_i, 1\le w_i\le S) — an edge in the tree with weight wiw_i.

It is guaranteed that the sum of nn for all tests does not exceed 21052\cdot 10^5.

Output

For each test, output the number of different graphs that satisfy the conditions, modulo 998244353998244353.

Sample Input 1

4
2 5
1 2 4
4 5
1 2 2
2 3 4
3 4 3
5 6
1 2 3
1 3 2
3 4 6
3 5 1
10 200
1 2 3
2 3 33
3 4 200
1 5 132
5 6 1
5 7 29
7 8 187
7 9 20
7 10 4

Sample Output 1

1
8
80
650867886

Note

In the first sample, there is only one graph, which is the given tree.

In the second samle, the given tree looks like this:

All possible graphs for the second sample are shown below, the minimum spanning tree is highlighted in red: