func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 3e5 + 10;   long long int dp1[N], dp2[N], Sa[N], Sw[N], dp[20][N], A[N];   int P[20][N], H[N], n, q;   vector<pair<int, int> > adj[N];   void preDFS(int v, int p = -1) {     if (!~p) P[0][v] = v;     for (int i = 1; i < 20; i++) P[i][v] = P[i - 1][P[i - 1][v]];     for (pair<int, int> u : adj[v]) {       if (u.first != p) {         P[0][u.first] = v;         H[u.first] = H[v] + 1;         Sw[u.first] = Sw[v] + u.second, Sa[u.first] = Sa[v] + A[u.first];         preDFS(u.first, v);       }     }   }   int getpar(int v, int h) {     for (int i = h; i; i -= i & -i) v = P[__builtin_ctz(i)][v];     return v;   }   int LCA(int u, int v) {     if (H[u] < H[v]) swap(u, v);     u = getpar(u, H[u] - H[v]);     if (u == v) return v;     for (int i = 19; ~i; i--)       if (P[i][u] != P[i][v]) u = P[i][u], v = P[i][v];     return P[0][v];   }   void DFSdn(int v, int p = -1) {     for (pair<int, int> u : adj[v]) {       if (u.first != p)         DFSdn(u.first, v),             dp1[v] += max(0ll, dp1[u.first] - 2 * u.second + A[u.first]);     }   }   void DFSup(int v, int p = -1) {     for (pair<int, int> u : adj[v]) {       if (u.first != p) {         dp2[u.first] =             max(0ll, A[v] + dp2[v] + dp1[v] -                          max(0ll, dp1[u.first] - 2 * u.second + A[u.first]));         dp2[u.first] = max(0ll, dp2[u.first] - 2 * u.second);         DFSup(u.first, v);       }     }   }   void NIMA(int v, int p = -1) {     for (pair<int, int> u : adj[v]) {       if (u.first != p) {         dp[0][u.first] =             dp1[v] - max(0ll, dp1[u.first] - 2 * u.second + A[u.first]);         NIMA(u.first, v);       }     }   }   long long int get(int v, int h) {     long long int ret = 0;     for (int i = h; i; i -= i & -i)       ret += dp[__builtin_ctz(i)][v], v = P[__builtin_ctz(i)][v];     return ret;   }   int main() {     scanf( %d%d , &n, &q);     for (int i = 1; i <= n; i++) scanf( %lld , &A[i]);     for (int i = 1; i < n; i++) {       int u, v, w;       scanf( %d%d%d , &u, &v, &w);       adj[u].push_back({v, w});       adj[v].push_back({u, w});     }     preDFS(1);     DFSdn(1);     DFSup(1);     NIMA(1);     for (int i = 1; i < 20; i++)       for (int j = 1; j <= n; j++)         dp[i][j] = dp[i - 1][j] + dp[i - 1][P[i - 1][j]];     for (; q; q--) {       int u, v;       scanf( %d%d , &u, &v);       if (H[u] < H[v]) swap(u, v);       if (u == v) {         printf( %lld n , dp1[u] + dp2[u] + A[u]);         continue;       }       int p = LCA(u, v);       long long int a = get(u, H[u] - H[p]), b = get(v, H[v] - H[p]);       long long int ret =           Sa[u] - Sa[p] + A[p] + Sa[v] - Sa[p] - (Sw[u] - Sw[p] + Sw[v] - Sw[p]);       printf( %lld n , a + b + dp2[p] - dp1[p] + ret + dp1[u] + dp1[v]);     }     return 0;   }   