题目描述
Problem Statement
You are given a tree with N vertices.
For each $i = 1, 2, \ldots, N-1$, the i-th edge connects Vertex u_i and Vertex v_i and has a weight w_i.
Consider choosing some of the N-1 edges (possibly none or all).
Here, for each $i = 1, 2, \ldots, N,$ one may choose at most d_i edges incident to Vertex i.
Find the maximum possible total weight of the chosen edges.
Input
Input is given from Standard Input in the following format:
N
$d_1 d_2 \ldots d_N$
u_1 v_1 w_1
u_2 v_2 w_2
$\vdots$
u_{N-1} v_{N-1} w_{N-1}
Output
Print the answer.
Constraints
- $2 \leq N \leq 3 \times 10^5$
- $1 \leq u_i, v_i \leq N$
- -$10^9 \leq w_i \leq 10^9$
- d_i is a non-negative integer not exceeding the degree of Vertex i.
- The given graph is a tree.
- All values in input are integers.
Sample Input 1
7
1 2 1 0 2 1 1
1 2 8
2 3 9
2 4 10
2 5 -3
5 6 8
5 7 3
Sample Output 1
28
If you choose the 1-st, 2-nd, 5-th, and 6-th edges, the total weight of those edges is 8 + 9 + 8 + 3 = 28. This is the maximum possible.
Sample Input 2
20
0 2 0 1 2 1 0 0 3 0 1 1 1 1 0 0 3 0 1 2
4 9 583
4 6 -431
5 9 325
17 6 131
17 2 -520
2 16 696
5 7 662
17 15 845
7 8 307
13 7 849
9 19 242
20 6 909
7 11 -775
17 18 557
14 20 95
18 10 646
4 3 -168
1 3 -917
11 12 30
Sample Output 2
2184
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分