#include #include #include using std::cin; using std::cout; using std::endl; const int N = 100005; int n, u, v, w, k, a[N]; std::string op; std::pair t[N]; std::vector g[N]; // Heavy Path Decomposition int cnt, b[N], id[N], fa[N], dep[N], siz[N], son[N], top[N]; void dfs1(int, int); void dfs2(int, int); void modify_path(int, int, int); void change_path(int, int, int); int query_path(int, int); // Segment Tree void pushup(int); void pushdown(int); void build(int, int, int); void modify(int, int, int, int); void change(int, int, int, int); int query(int, int, int); int main() { cin >> n; for (int i = 1; i < n; i++) { cin >> t[i].first >> t[i].second >> a[i]; g[t[i].first].push_back(t[i].second); g[t[i].second].push_back(t[i].first); } dfs1(1, 1); dfs2(1, 1); build(1, 1, n); for (int i = 1; i < n; i++) { if (dep[t[i].first] < dep[t[i].second]) std::swap(t[i].first, t[i].second); modify(1, id[t[i].first], id[t[i].first], a[i]); } while (cin >> op, op != "Stop") { if (op == "Change") { cin >> k >> w; change(1, id[t[k].first], id[t[k].first], w); } else if (op == "Cover") { cin >> u >> v >> w; change_path(u, v, w); } else if (op == "Add") { cin >> u >> v >> w; modify_path(u, v, w); } else { cin >> u >> v; cout << query_path(u, v) << endl; } } return 0; } // === Heavy Path Decomposition === void dfs1(int u, int f) { fa[u] = f; dep[u] = dep[f] + 1; siz[u] = 1; for (int v : g[u]) { if (v == f) continue; dfs1(v, u); siz[u] += siz[v]; if (siz[son[u]] < siz[v]) son[u] = v; } } void dfs2(int u, int t) { id[u] = ++cnt; top[u] = t; if (!son[u]) return; dfs2(son[u], t); for (int v : g[u]) { if (v == fa[u]) continue; if (v == son[u]) continue; dfs2(v, v); } } void modify_path(int u, int v, int d) { while (top[u] != top[v]) { if (dep[top[u]] < dep[top[v]]) std::swap(u, v); modify(1, id[top[u]], id[u], d); u = fa[top[u]]; } if (dep[u] < dep[v]) std::swap(u, v); modify(1, id[son[v]], id[u], d); } void change_path(int u, int v, int d) { while (top[u] != top[v]) { if (dep[top[u]] < dep[top[v]]) std::swap(u, v); change(1, id[top[u]], id[u], d); u = fa[top[u]]; } if (dep[u] < dep[v]) std::swap(u, v); change(1, id[son[v]], id[u], d); } int query_path(int u, int v) { int res = 0; while (top[u] != top[v]) { if (dep[top[u]] < dep[top[v]]) std::swap(u, v); res = std::max(res, query(1, id[top[u]], id[u])); u = fa[top[u]]; } if (dep[u] < dep[v]) std::swap(u, v); res = std::max(res, query(1, id[son[v]], id[u])); return res; } // == Segment Tree === struct node { int l, r, m, da, dc; node() : l(0), r(0), m(0), da(0), dc(-1) {} node(int _l, int _r) : l(_l), r(_r), m(0), da(0), dc(-1) {} } tr[N << 2]; inline void pushup(int u) { tr[u].m = std::max(tr[u << 1].m, tr[u << 1 | 1].m); } inline void pushdown(int u) { node &root = tr[u], &left = tr[u << 1], &right = tr[u << 1 | 1]; if (root.dc != -1) { left.m = right.m = root.dc; left.da = right.da = 0; left.dc = right.dc = root.dc; root.dc = -1; } left.m += root.da; left.da += root.da; right.m += root.da; right.da += root.da; root.da = 0; } void build(int u, int l, int r) { tr[u] = node(l, r); if (l == r) { tr[u].m = b[l]; return; } int mid = l + r >> 1; build(u << 1, l, mid); build(u << 1 | 1, mid + 1, r); pushup(u); } void modify(int u, int l, int r, int d) { if (l <= tr[u].l && tr[u].r <= r) { tr[u].m += d; tr[u].da += d; return; } int mid = tr[u].l + tr[u].r >> 1; pushdown(u); if (l <= mid) modify(u << 1, l, r, d); if (r > mid) modify(u << 1 | 1, l, r, d); pushup(u); } void change(int u, int l, int r, int d) { if (l <= tr[u].l && tr[u].r <= r) { tr[u].m = d; tr[u].da = 0; tr[u].dc = d; return; } int mid = tr[u].l + tr[u].r >> 1; pushdown(u); if (l <= mid) change(u << 1, l, r, d); if (r > mid) change(u << 1 | 1, l, r, d); pushup(u); } int query(int u, int l, int r) { if (l <= tr[u].l && tr[u].r <= r) return tr[u].m; pushdown(u); int mid = tr[u].l + tr[u].r >> 1; int res = 0; if (l <= mid) res = std::max(res, query(u << 1, l, r)); if (r > mid) res = std::max(res, query(u << 1 | 1, l, r)); return res; }