#include #include #include using std::cin; using std::cout; using std::endl; const int N = 100005; int n, x, t, a, b, u[N], v[N], w[N]; std::string op; std::vector g[N]; // Heavy Path Decomposition int cnt, id[N], fa[N], dep[N], son[N], siz[N], top[N]; void dfs1(int, int); void dfs2(int, int); int query_path(int, int); // Segment Tree void pushup(int); void pushdown(int); void build(int, int, int); void change(int, int, int); int query(int, int, int); int main() { cin >> n; for (int i = 1; i < n; i++) { cin >> u[i] >> v[i] >> w[i]; g[u[i]].push_back(v[i]); g[v[i]].push_back(u[i]); } dfs1(1, 1); dfs2(1, 1); build(1, 1, n); for (int i = 1; i < n; i++) { if (dep[u[i]] < dep[v[i]]) std::swap(u[i], v[i]); change(1, id[u[i]], w[i]); } while (cin >> op, op != "DONE") { if (op == "CHANGE") { cin >> x >> t; change(1, id[u[x]], t); } else { cin >> a >> b; cout << (a == b ? 0 : query_path(a, b)) << 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); } } 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; node() : l(0), r(0), m(0) {} node(int _l, int _r) : l(_l), r(_r), m(0) {} } tr[N << 2]; inline void pushup(int u) { tr[u].m = std::max(tr[u << 1].m, tr[u << 1 | 1].m); } void build(int u, int l, int r) { tr[u] = node(l, r); if (l == r) return; int mid = l + r >> 1; build(u << 1, l, mid); build(u << 1 | 1, mid + 1, r); pushup(u); } void change(int u, int x, int d) { if (tr[u].l == tr[u].r) { tr[u].m = d; return; } int mid = tr[u].l + tr[u].r >> 1; if (x <= mid) { change(u << 1, x, d); } else { change(u << 1 | 1, x, d); } pushup(u); } int query(int u, int l, int r) { if (l <= tr[u].l && tr[u].r <= r) return tr[u].m; 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; }