func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 2e5 + 5;   vector<int> E;   vector<int> a[N];   int value[N];   long long down[N];   long long max_path[N];   int n;   long long calc_down(int edge_index) {     long long &ans = down[edge_index];     if (ans != -1) return ans;     int v = E[edge_index];     ans = value[v];     for (int e : a[v])       if (e != (edge_index ^ 1)) ans = max(ans, calc_down(e) + value[v]);     return ans;   }   long long calc_max_path(int edge_index) {     long long &ans = max_path[edge_index];     if (ans != -1) return ans;     int v = E[edge_index];     long long first = 0, second = 0;     for (int e : a[v])       if (e != (edge_index ^ 1)) {         long long cur = calc_down(e);         if (first <= cur)           second = first, first = cur;         else if (second < cur)           second = cur;         ans = max(ans, calc_max_path(e));       }     return ans = max(ans, first + second + value[v]);   }   int main() {     ios::sync_with_stdio(false);     cin >> n;     for (int i = 1; i <= n; ++i) cin >> value[i];     for (int i = 1; i < n; ++i) {       int u, v;       cin >> u >> v;       a[u].push_back(E.size());       E.push_back(v);       a[v].push_back(E.size());       E.push_back(u);     }     memset(down, -1, sizeof down);     memset(max_path, -1, sizeof max_path);     long long ans = 0;     for (int i = 0; i < E.size(); i += 2)       ans = max(ans, calc_max_path(i) + calc_max_path(i ^ 1));     cout << ans << endl;   }   