#define PROBLEM "https://yukicoder.me/problems/no/1094" #include using namespace std; template struct LowestCommonAncestor{ int mx_level; vector> parent; vector depth; vector dist; LowestCommonAncestor(const vector>>& G, int root=0) { init(G, root); } LowestCommonAncestor(const vector>& G, int root=0) { init(G, root); } template void init(const GType& G, int root) { int N = G.size(); mx_level = 1; while((1 << mx_level) < N) mx_level++; parent.assign(mx_level, vector(N, -1)); depth.assign(N, -1); dist.assign(N, -1); dfs(G, root, -1, 0, 0); for(int lv = 1; lv < mx_level; lv++) { for(int i = 0; i < N; i++) { if(parent[lv - 1][i] == -1) parent[lv][i] = -1; else parent[lv][i] = parent[lv - 1][parent[lv - 1][i]]; } } } template void dfs(const GType& G, int v, int p, int dep, T dis) { parent[0][v] = p; depth[v] = dep; dist[v] = dis; if constexpr (is_same_v>>>) { for(auto [nv, c] : G[v]) { if(nv == p) continue; dfs(G, nv, v, dep + 1, dis + c); } } else if constexpr (is_same_v>>) { for(int nv : G[v]) { if(nv == p) continue; dfs(G, nv, v, dep + 1, dis + T(1)); } } } int lca(int u, int v) { if(depth[u] < depth[v]) swap(u, v); for(int lv = 0; lv < mx_level; lv++) { if(((depth[u] - depth[v]) >> lv) & 1) u = parent[lv][u]; } if(u == v) return u; for(int lv = mx_level - 1; lv >= 0; lv--) { if(parent[lv][u] != parent[lv][v]) { u = parent[lv][u]; v = parent[lv][v]; } } return parent[0][u]; } T dist_bitween(int u, int v) { return dist[u] + dist[v] - 2 * dist[lca(u, v)]; } int path_len(int u, int v) { return depth[u] + depth[v] - 2 * depth[lca(u, v)]; } }; int main() { cin.tie(nullptr); ios::sync_with_stdio(false); int N; cin >> N; vector>> G(N); for(int i = 0; i < N - 1; i++) { int a, b, c; cin >> a >> b >> c; a--; b--; G[a].push_back({b, c}); G[b].push_back({a, c}); } LowestCommonAncestor lca(G); int Q; cin >> Q; while(Q--) { int s, t; cin >> s >> t; s--; t--; cout << lca.dist_bitween(s, t) << "\n"; } return 0; }