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问题1378--City Upgrading

1378: City Upgrading

[命题人 : ]
时间限制 : 1.000 sec  内存限制 : 128 MiB

题目描述

The city where crazyzhk resides is structured as a tree. On a certain day, the city’s network needs to be upgraded. To achieve this goal, routers need to be deployed. Each router covers the node it is placed on and its neighboring nodes. There is a cost ai associated with placing a router at each node. The question is: How can the routers be deployed at minimum cost to ensure that every node is covered?

输入

The input consists of multiple test cases. The first line contains a single integer t(1 ≤ t ≤ 1000) — the number of test cases. Description of the test cases follows. 
The first line of each test case contains a integer n (1 ≤ n ≤ 105 ) — the number of the vertices in the given tree. 
The second line of each case are n integers ai (1 ≤ ai ≤ 105 ),denoting the cost of setting up a router at each node. 
Each of the next n − 1 lines contains two integers u and v (1 ≤ u, v ≤ n, u≠ v) meaning that there is an edge between vertices u and v in the tree. 
The data guarantees that the sum of n will not exceed 2 · 105

输出

For each test case print a single integer ——the minimum cost to ensure that every node is covered

样例输入 Copy

2
7
13 20 1 20 6 9 8
1 2
1 3
2 4
2 5
3 6
5 7
4
1 17 13 4
1 2
1 3
3 4

样例输出 Copy

27
5