2017-10-25 04:15

# Fantasia

• as
• components
• x
• lines
• each

Problem Description
Professor Zhang has an undirected graph G with n vertices and m edges. Each vertex is attached with a weight w_i. Let G_i be the graph after deleting the i-th vertex from graph G. Professor Zhang wants to find the weight of G_1, G_2, ..., G_n.

The weight of a graph G is defined as follows:

1. If G is connected, then the weight of G is the product of the weight of each vertex in G.
2. Otherwise, the weight of G is the sum of the weight of all the connected components of G.

A connected component of an undirected graph G is a subgraph in which any two vertices are connected to each other by paths, and which is connected to no additional vertices in G.

Input
There are multiple test cases. The first line of input contains an integer T, indicating the number of test cases. For each test case:

The first line contains two integers n and m (2 \le n \le 10^5, 1 \le m \le 2 \times 10^5) -- the number of vertices and the number of edges.

The second line contains n integers w_1, w_2, ..., w_n (1 \le w_i \le 10^9), denoting the weight of each vertex.

In the next m lines, each contains two integers x_i and y_i (1 \le x_i, y_i \le n, x_i \ne y_i), denoting an undirected edge.

There are at most 1000 test cases and \sum n, \sum m \le 1.5 \times 10^6.

Output
For each test case, output an integer S = (\sum\limits_{i=1}^{n}i\cdot z_i) \text{ mod } (10^9 + 7), where z_i is the weight of G_i.

Sample Input
1
3 2
1 2 3
1 2
2 3

Sample Output
20

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