[ICPC 2021 Nanjing R] Paimon's Tree

Luogu
IDLGP9846
Time4000ms
Memory256MB
DifficultyP6
动态规划 DP2021Special JudgeO2优化ICPC南京
Paimon has found a tree with $(n + 1)$ initially white vertices in her left pocket and decides to play with it. A tree with $(n + 1)$ nodes is an undirected connected graph with $n$ edges. Paimon will give you an integer sequence $a_1, a_2, \cdots, a_n$ of length $n$. We first need to select a vertex in the tree and paint it black. Then we perform the following operation $n$ times. During the $i$-th operation, we select a white vertex $x_i$ which is directly connected with a black vertex $y_i$ by an edge, set the weight of that edge to $a_i$ and also paint $x_i$ in black. After these $n$ operations we get a tree whose edges are all weighted. What's the maximum length of the diameter of the weighted tree if we select the vertices optimally? The diameter of a weighted tree is the longest simple path in that tree. The length of a simple path is the sum of the weights of all edges in that path. ## Input There are multiple test cases. The first line of the input contains an integer $T$ ($1 \le T \le 5 \times 10^3$) indicating the number of test cases. For each test case: The first line contains an integer $n$ ($1 \le n \le 150$) indicating the length of the sequence. The second line contains $n$ integers $a_1, a_2, \cdots, a_n$ ($1 \le a_i \le 10^9$) indicating the sequence. For the following $n$ lines, the $i$-th line contains two integers $u_i$ and $v_i$ ($1 \le u_i, v_i \le n + 1$) indicating that there is an edge connecting vertex $u_i$ and $v_i$ in the tree. It's guaranteed that there is at most $10$ test cases satisfying $n > 20$. ## Output For each test case output one line containing one integer indicating the maximum length of the diameter of the tree. [samples] ## Note For the first sample test case, we select the vertices in the order of $1, 3, 4, 5, 2, 6$, resulting in the weighted tree of the following image. It's obvious that the longest simple path is of length $16$. ![](https://cdn.luogu.com.cn/upload/image_hosting/vamukdcv.png)
Samples
Input #1
2
5
1 7 3 5 4
1 3
2 3
3 4
4 5
4 6
1
1000000000
1 2
Output #1
16
1000000000
API Response (JSON)
{
  "problem": {
    "name": "[ICPC 2021 Nanjing R] Paimon's Tree",
    "description": {
      "content": "Paimon has found a tree with $(n + 1)$ initially white vertices in her left pocket and decides to play with it. A tree with $(n + 1)$ nodes is an undirected connected graph with $n$ edges. Paimon wil",
      "description_type": "Markdown"
    },
    "platform": "Luogu",
    "limit": {
      "time_limit": 4000,
      "memory_limit": 262144
    },
    "difficulty": {
      "LuoguStyle": "P6"
    },
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "LGP9846"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Paimon has found a tree with $(n + 1)$ initially white vertices in her left pocket and decides to play with it. A tree with $(n + 1)$ nodes is an undirected connected graph with $n$ edges.\n\nPaimon wil...",
      "is_translate": false,
      "language": "English"
    }
  ]
}
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