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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. long long sum[500000 + 5];
  5. long long b[500000 + 5];
  6.  
  7. void DFS(long long node, vector<long long> G[], long long used[], long long parent[]) {
  8.     used[node] = 1;
  9.  
  10.     for (long long neighbour : G[node]) {
  11.         if (used[neighbour] == 0) {
  12.             parent[neighbour] = node;
  13.             DFS(neighbour, G, used, parent);
  14.         }
  15.     }
  16.  
  17.     long long best = 0;
  18.  
  19.     for (long long child : G[node]) {
  20.         if (child != parent[node]) {
  21.             best = max(best, sum[child]);
  22.         }
  23.     }
  24.  
  25.     sum[node] = b[node] + best;
  26. }
  27.  
  28. int main() {
  29.     long long n;
  30.     cin >> n;
  31.  
  32.     vector<long long> G[n + 1];
  33.  
  34.     for (long long i = 1; i <= n; i++) {
  35.         cin >> b[i];
  36.     }
  37.  
  38.     for (long long i = 1; i <= n - 1; i++) {
  39.         long long u, v;
  40.         cin >> u >> v;
  41.  
  42.         G[u].push_back(v);
  43.         G[v].push_back(u);
  44.     }
  45.  
  46.     long long used[n + 1] = {};
  47.     long long parent[n + 1] = {};
  48.  
  49.     DFS(1, G, used, parent);
  50.  
  51.     long long answer = -1000000000000000LL;
  52.  
  53.     for (long long i = 1; i <= n; i++) {
  54.         answer = max(answer, sum[i]);
  55.     }
  56.  
  57.     cout << answer;
  58.  
  59.     return 0;
  60. }
Success #stdin #stdout 0.01s 5548KB
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https://ideone.com/88Mxxc
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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