#line 1 "a.cpp" /** * author: nok0 * created: 2022.02.04 22:21:34 **/ #line 1 "/Users/nok0/Documents/Programming/nok0/cftemp.hpp" #include using namespace std; #pragma region Macros // rep macro #define foa(v, a) for(auto &v : a) #define REPname(a, b, c, d, e, ...) e #define REP(...) REPname(__VA_ARGS__, REP3, REP2, REP1, REP0)(__VA_ARGS__) #define REP0(x) for(int i = 0; i < (x); ++i) #define REP1(i, x) for(int i = 0; i < (x); ++i) #define REP2(i, l, r) for(int i = (l); i < (r); ++i) #define REP3(i, l, r, c) for(int i = (l); i < (r); i += (c)) #define REPSname(a, b, c, ...) c #define REPS(...) REPSname(__VA_ARGS__, REPS1, REPS0)(__VA_ARGS__) #define REPS0(x) for(int i = 1; i <= (x); ++i) #define REPS1(i, x) for(int i = 1; i <= (x); ++i) #define RREPname(a, b, c, d, e, ...) e #define RREP(...) RREPname(__VA_ARGS__, RREP3, RREP2, RREP1, RREP0)(__VA_ARGS__) #define RREP0(x) for(int i = (x)-1; i >= 0; --i) #define RREP1(i, x) for(int i = (x)-1; i >= 0; --i) #define RREP2(i, r, l) for(int i = (r)-1; i >= (l); --i) #define RREP3(i, r, l, c) for(int i = (r)-1; i >= (l); i -= (c)) #define RREPSname(a, b, c, ...) c #define RREPS(...) RREPSname(__VA_ARGS__, RREPS1, RREPS0)(__VA_ARGS__) #define RREPS0(x) for(int i = (x); i >= 1; --i) #define RREPS1(i, x) for(int i = (x); i >= 1; --i) // name macro #define pb push_back #define eb emplace_back #define SZ(x) ((int)(x).size()) #define all(x) (x).begin(), (x).end() #define rall(x) (x).rbegin(), (x).rend() #define popcnt(x) __builtin_popcountll(x) template using V = std::vector; template using VV = std::vector>; template using pqup = std::priority_queue, std::greater>; using ll = long long; using ld = long double; using int128 = __int128_t; using pii = std::pair; using pll = std::pair; // input macro template std::istream &operator>>(std::istream &is, std::pair &p) { is >> p.first >> p.second; return is; } template std::istream &operator>>(std::istream &is, std::vector &v) { for(T &i : v) is >> i; return is; } std::istream &operator>>(std::istream &is, __int128_t &a) { std::string s; is >> s; __int128_t ret = 0; for(int i = 0; i < s.length(); i++) if('0' <= s[i] and s[i] <= '9') ret = 10 * ret + s[i] - '0'; a = ret * (s[0] == '-' ? -1 : 1); return is; } namespace scanner { void scan(int &a) { std::cin >> a; } void scan(long long &a) { std::cin >> a; } void scan(std::string &a) { std::cin >> a; } void scan(char &a) { std::cin >> a; } void scan(char a[]) { std::scanf("%s", a); } void scan(double &a) { std::cin >> a; } void scan(long double &a) { std::cin >> a; } template void scan(std::pair &p) { std::cin >> p; } template void scan(std::vector &a) { std::cin >> a; } void INPUT() {} template void INPUT(Head &head, Tail &...tail) { scan(head); INPUT(tail...); } } // namespace scanner #define VEC(type, name, size) \ std::vector name(size); \ scanner::INPUT(name) #define VVEC(type, name, h, w) \ std::vector> name(h, std::vector(w)); \ scanner::INPUT(name) #define INT(...) \ int __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define LL(...) \ long long __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define STR(...) \ std::string __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define CHAR(...) \ char __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define DOUBLE(...) \ double __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) #define LD(...) \ long double __VA_ARGS__; \ scanner::INPUT(__VA_ARGS__) // output-macro template std::ostream &operator<<(std::ostream &os, const std::pair &p) { os << p.first << " " << p.second; return os; } template std::ostream &operator<<(std::ostream &os, const std::vector &a) { for(int i = 0; i < int(a.size()); ++i) { if(i) os << " "; os << a[i]; } return os; } std::ostream &operator<<(std::ostream &dest, __int128_t &value) { std::ostream::sentry s(dest); if(s) { __uint128_t tmp = value < 0 ? -value : value; char buffer[128]; char *d = std::end(buffer); do { --d; *d = "0123456789"[tmp % 10]; tmp /= 10; } while(tmp != 0); if(value < 0) { --d; *d = '-'; } int len = std::end(buffer) - d; if(dest.rdbuf()->sputn(d, len) != len) { dest.setstate(std::ios_base::badbit); } } return dest; } template void print(const T a) { std::cout << a << '\n'; } template void print(Head H, Tail... T) { std::cout << H << ' '; print(T...); } template void printel(const T a) { std::cout << a << '\n'; } template void printel(const std::vector &a) { for(const auto &v : a) std::cout << v << '\n'; } template void printel(Head H, Tail... T) { std::cout << H << '\n'; printel(T...); } void Yes(const bool b = true) { std::cout << (b ? "Yes\n" : "No\n"); } void No() { std::cout << "No\n"; } void YES(const bool b = true) { std::cout << (b ? "YES\n" : "NO\n"); } void NO() { std::cout << "NO\n"; } void err(const bool b = true) { if(b) { std::cout << "-1\n", exit(0); } } //debug macro namespace debugger { template void view(const std::vector &a) { std::cerr << "{ "; for(const auto &v : a) { std::cerr << v << ", "; } std::cerr << "\b\b }"; } template void view(const std::vector> &a) { std::cerr << "{\n"; for(const auto &v : a) { std::cerr << "\t"; view(v); std::cerr << "\n"; } std::cerr << "}"; } template void view(const std::vector> &a) { std::cerr << "{\n"; for(const auto &p : a) std::cerr << "\t(" << p.first << ", " << p.second << ")\n"; std::cerr << "}"; } template void view(const std::map &m) { std::cerr << "{\n"; for(const auto &p : m) std::cerr << "\t[" << p.first << "] : " << p.second << "\n"; std::cerr << "}"; } template void view(const std::pair &p) { std::cerr << "(" << p.first << ", " << p.second << ")"; } template void view(const std::set &s) { std::cerr << "{ "; for(auto &v : s) { view(v); std::cerr << ", "; } std::cerr << "\b\b }"; } template void view(const T &e) { std::cerr << e; } } // namespace debugger #ifdef LOCAL void debug_out() {} template void debug_out(Head H, Tail... T) { debugger::view(H); std::cerr << ", "; debug_out(T...); } #define debug(...) \ do { \ std::cerr << __LINE__ << " [" << #__VA_ARGS__ << "] : ["; \ debug_out(__VA_ARGS__); \ std::cerr << "\b\b]\n"; \ } while(false) #else #define debug(...) (void(0)) #endif // vector macro template int lb(const std::vector &a, const T x) { return std::distance((a).begin(), std::lower_bound((a).begin(), (a).end(), (x))); } template int ub(const std::vector &a, const T x) { return std::distance((a).begin(), std::upper_bound((a).begin(), (a).end(), (x))); } template void UNIQUE(std::vector &a) { std::sort(a.begin(), a.end()); a.erase(std::unique(a.begin(), a.end()), a.end()); } template std::vector press(std::vector &a) { auto res = a; UNIQUE(res); for(auto &v : a) v = lb(res, v); return res; } #define SORTname(a, b, c, ...) c #define SORT(...) SORTname(__VA_ARGS__, SORT1, SORT0, ...)(__VA_ARGS__) #define SORT0(a) std::sort((a).begin(), (a).end()) #define SORT1(a, c) std::sort((a).begin(), (a).end(), [](const auto x, const auto y) { return x c y; }) template void ADD(std::vector &a, const T x = 1) { for(auto &v : a) v += x; } template void SUB(std::vector &a, const T x = 1) { for(auto &v : a) v -= x; } std::vector> rle(const string &s) { int n = s.size(); std::vector> ret; for(int l = 0; l < n;) { int r = l + 1; for(; r < n and s[l] == s[r]; r++) {} ret.emplace_back(s[l], r - l); l = r; } return ret; } template std::vector> rle(const std::vector &v) { int n = v.size(); std::vector> ret; for(int l = 0; l < n;) { int r = l + 1; for(; r < n and v[l] == v[r]; r++) {} ret.emplace_back(v[l], r - l); l = r; } return ret; } std::vector iota(int n) { std::vector p(n); std::iota(p.begin(), p.end(), 0); return p; } template struct cum_vector { public: cum_vector() = default; template cum_vector(const std::vector &vec) : cum((int)vec.size() + 1) { for(int i = 0; i < (int)vec.size(); i++) cum[i + 1] = cum[i] + vec[i]; } T prod(int l, int r) { return cum[r] - cum[l]; } private: std::vector cum; }; // math macro template inline bool chmin(T &a, const U &b) { return a > b ? a = b, true : false; } template inline bool chmax(T &a, const U &b) { return a < b ? a = b, true : false; } template T divup(T x, T y) { return (x + y - 1) / y; } template T POW(T a, long long n) { T ret = 1; while(n) { if(n & 1) ret *= a; a *= a; n >>= 1; } return ret; } // modpow long long POW(long long a, long long n, const int mod) { long long ret = 1; a = (a % mod + mod) % mod; while(n) { if(n & 1) (ret *= a) %= mod; (a *= a) %= mod; n >>= 1; } return ret; } template T bin_search(T ok, T ng, const F &f) { while(abs(ok - ng) > 1) { T mid = (ok + ng) >> 1; (f(mid) ? ok : ng) = mid; } return ok; } template T bin_search(T ok, T ng, const F &f, int loop) { for(int i = 0; i < loop; i++) { T mid = (ok + ng) / 2; (f(mid) ? ok : ng) = mid; } return ok; } // others struct fast_io { fast_io() { ios::sync_with_stdio(false); cin.tie(nullptr); cout << fixed << setprecision(15); } } fast_io_; const int inf = 1e9; const ll INF = 1e18; #pragma endregion void main_(); int main() { main_(); return 0; } #line 10 "/Users/nok0/Documents/Programming/nok0/graph/graph.hpp" struct Edge { int to; long long cost; Edge() = default; Edge(int to_, long long cost_) : to(to_), cost(cost_) {} bool operator<(const Edge &a) const { return cost < a.cost; } bool operator>(const Edge &a) const { return cost > a.cost; } friend std::ostream &operator<<(std::ostream &s, Edge &a) { s << "to: " << a.to << ", cost: " << a.cost; return s; } }; class graph { std::vector> edges; template struct rec_lambda { F f; rec_lambda(F &&f_) : f(std::forward(f_)) {} template auto operator()(Args &&...args) const { return f(*this, std::forward(args)...); } }; public: inline const std::vector &operator[](int k) const { return edges[k]; } inline std::vector &operator[](int k) { return edges[k]; } int size() const { return edges.size(); } void resize(const int n) { edges.resize(n); } graph() = default; graph(int n) : edges(n) {} graph(int n, int e, bool weight = 0, bool directed = 0, int idx = 1) : edges(n) { input(e, weight, directed, idx); } const long long INF = 3e18; void input(int e = -1, bool weight = 0, bool directed = false, int idx = 1) { if(e == -1) e = size() - 1; while(e--) { int u, v; long long cost = 1; std::cin >> u >> v; if(weight) std::cin >> cost; u -= idx, v -= idx; edges[u].emplace_back(v, cost); if(!directed) edges[v].emplace_back(u, cost); } } void add_edge(int u, int v, long long cost = 1, bool directed = false, int idx = 0) { u -= idx, v -= idx; edges[u].emplace_back(v, cost); if(!directed) edges[v].emplace_back(u, cost); } // Ο(V+E) std::vector bfs(int s) { std::vector dist(size(), INF); std::queue que; dist[s] = 0; que.push(s); while(!que.empty()) { int v = que.front(); que.pop(); for(auto &e : edges[v]) { if(dist[e.to] != INF) continue; dist[e.to] = dist[v] + e.cost; que.push(e.to); } } return dist; } // Ο(V+E) // constraint: cost of each edge is zero or one std::vector zero_one_bfs(int s) { std::vector dist(size(), INF); std::deque deq; dist[s] = 0; deq.push_back(s); while(!deq.empty()) { int v = deq.front(); deq.pop_front(); for(auto &e : edges[v]) { assert(0LL <= e.cost and e.cost < 2LL); if(e.cost and dist[e.to] > dist[v] + 1) { dist[e.to] = dist[v] + 1; deq.push_back(e.to); } else if(!e.cost and dist[e.to] > dist[v]) { dist[e.to] = dist[v]; deq.push_front(e.to); } } } return dist; } // Ο((E+V)logV) // cannot reach: INF std::vector dijkstra(int s) { // verified std::vector dist(size(), INF); const auto compare = [](const std::pair &a, const std::pair &b) { return a.first > b.first; }; std::priority_queue, std::vector>, decltype(compare)> que{compare}; dist[s] = 0; que.emplace(0, s); while(!que.empty()) { std::pair p = que.top(); que.pop(); int v = p.second; if(dist[v] < p.first) continue; for(auto &e : edges[v]) { if(dist[e.to] > dist[v] + e.cost) { dist[e.to] = dist[v] + e.cost; que.emplace(dist[e.to], e.to); } } } return dist; } // Ο(VE) // cannot reach: INF // negative cycle: -INF std::vector bellman_ford(int s) { // verified int n = size(); std::vector res(n, INF); res[s] = 0; for(int loop = 0; loop < n - 1; loop++) { for(int v = 0; v < n; v++) { if(res[v] == INF) continue; for(auto &e : edges[v]) { res[e.to] = std::min(res[e.to], res[v] + e.cost); } } } std::queue que; std::vector chk(n); for(int v = 0; v < n; v++) { if(res[v] == INF) continue; for(auto &e : edges[v]) { if(res[e.to] > res[v] + e.cost and !chk[e.to]) { que.push(e.to); chk[e.to] = 1; } } } while(!que.empty()) { int now = que.front(); que.pop(); for(auto &e : edges[now]) { if(!chk[e.to]) { chk[e.to] = 1; que.push(e.to); } } } for(int i = 0; i < n; i++) if(chk[i]) res[i] = -INF; return res; } // Ο(V^3) std::vector> warshall_floyd() { // verified int n = size(); std::vector> dist(n, std::vector(n, INF)); for(int i = 0; i < n; i++) dist[i][i] = 0; for(int i = 0; i < n; i++) for(auto &e : edges[i]) dist[i][e.to] = std::min(dist[i][e.to], e.cost); for(int k = 0; k < n; k++) for(int i = 0; i < n; i++) { if(dist[i][k] == INF) continue; for(int j = 0; j < n; j++) { if(dist[k][j] == INF) continue; dist[i][j] = std::min(dist[i][j], dist[i][k] + dist[k][j]); } } return dist; } // Ο(V) (using DFS) // if a directed cycle exists, return {} std::vector topological_sort() { // verified std::vector res; int n = size(); std::vector used(n, 0); bool not_DAG = false; for(int i = 0; i < n; i++) { rec_lambda([&](auto &&dfs, int k) -> void { if(not_DAG) return; if(used[k]) { if(used[k] == 1) not_DAG = true; return; } used[k] = 1; for(auto &e : edges[k]) dfs(e.to); used[k] = 2; res.push_back(k); })(i); } if(not_DAG) return std::vector{}; std::reverse(res.begin(), res.end()); return res; } bool is_DAG() { return !topological_sort().empty(); } // verified // Ο(V) // array of the distance from each vertex to the most distant vertex std::vector height() { // verified auto vec1 = bfs(0); int v1 = -1, v2 = -1; long long dia = -1; for(int i = 0; i < int(size()); i++) if(dia < vec1[i]) dia = vec1[i], v1 = i; vec1 = bfs(v1); dia = -1; for(int i = 0; i < int(size()); i++) if(dia < vec1[i]) dia = vec1[i], v2 = i; auto vec2 = bfs(v2); for(int i = 0; i < int(size()); i++) if(vec1[i] < vec2[i]) vec1[i] = vec2[i]; return vec1; } // O(V+E) // vector<(int)(0 or 1)> // if it is not bipartite, return {} std::vector bipartite_grouping() { std::vector colors(size(), -1); auto dfs = [&](auto self, int now, int col) -> bool { colors[now] = col; for(auto &e : edges[now]) { if(col == colors[e.to]) return false; if(colors[e.to] == -1 and !self(self, e.to, !col)) return false; } return true; }; for(int i = 0; i < int(size()); i++) if(colors[i] == -1 and !dfs(dfs, i, 0)) return std::vector{}; return colors; } bool is_bipartite() { return !bipartite_grouping().empty(); } // Ο(V+E) // ((v1, v2), diameter) std::pair, long long> diameter() { // verified auto vec = bfs(0); int v1 = -1, v2 = -1; long long dia = -1; for(int i = 0; i < int(size()); i++) if(dia < vec[i]) dia = vec[i], v1 = i; vec = bfs(v1); dia = -1; for(int i = 0; i < int(size()); i++) if(dia < vec[i]) dia = vec[i], v2 = i; std::pair, long long> res = {{v1, v2}, dia}; return res; } // Ο(V+E) // return {s, v1, v2, ... t} std::vector diameter_path() { auto vec = bfs(0); int v1 = -1, v2 = -1; long long dia = -1; for(int i = 0; i < int(size()); i++) if(dia < vec[i]) dia = vec[i], v1 = i; auto vec2 = bfs(v1); dia = -1; for(int i = 0; i < int(size()); i++) if(dia < vec2[i]) dia = vec2[i], v2 = i; vec = bfs(v2); std::vector ret; auto dfs = [&](auto self, int now, int p) -> void { ret.emplace_back(now); if(now == v2) return; for(auto &[to, cost] : (*this)[now]) { if(vec[to] + vec2[to] == dia and to != p) self(self, to, now); } }; dfs(dfs, v1, -1); return ret; } // Ο(V+E) // return subtree_size, root = root std::vector subtree_size(const int root) { int n = size(); std::vector ret(n, 1); rec_lambda([&](auto &&dfs, int now, int p) -> void { for(auto &[to, cost] : (*this)[now]) { if(to == p) continue; dfs(to, now); ret[now] += ret[to]; } })(root, -1); return ret; } // Ο(ElogV) long long prim() { // verified long long res = 0; std::priority_queue, std::greater> que; for(auto &e : edges[0]) que.push(e); std::vector chk(size()); chk[0] = 1; int cnt = 1; while(cnt < size()) { auto e = que.top(); que.pop(); if(chk[e.to]) continue; cnt++; res += e.cost; chk[e.to] = 1; for(auto &e2 : edges[e.to]) que.push(e2); } return res; } // Ο(ElogE) long long kruskal() { // verified std::vector> Edges; for(int i = 0; i < int(size()); i++) for(auto &e : edges[i]) Edges.emplace_back(i, e.to, e.cost); std::sort(Edges.begin(), Edges.end(), [](const std::tuple &a, const std::tuple &b) { return std::get<2>(a) < std::get<2>(b); }); std::vector uf_data(size(), -1); auto root = [&uf_data](auto self, int x) -> int { if(uf_data[x] < 0) return x; return uf_data[x] = self(self, uf_data[x]); }; auto unite = [&uf_data, &root](int u, int v) -> bool { u = root(root, u), v = root(root, v); if(u == v) return false; if(uf_data[u] > uf_data[v]) std::swap(u, v); uf_data[u] += uf_data[v]; uf_data[v] = u; return true; }; long long ret = 0; for(auto &e : Edges) if(unite(std::get<0>(e), std::get<1>(e))) ret += std::get<2>(e); return ret; } graph build_mst() { std::vector> Edges; for(int i = 0; i < int(size()); i++) for(auto &e : edges[i]) Edges.emplace_back(i, e.to, e.cost); std::sort(Edges.begin(), Edges.end(), [](const std::tuple &a, const std::tuple &b) { return std::get<2>(a) < std::get<2>(b); }); std::vector uf_data(size(), -1); auto root = [&uf_data](auto self, int x) -> int { if(uf_data[x] < 0) return x; return uf_data[x] = self(self, uf_data[x]); }; auto unite = [&uf_data, &root](int u, int v) -> bool { u = root(root, u), v = root(root, v); if(u == v) return false; if(uf_data[u] > uf_data[v]) std::swap(u, v); uf_data[u] += uf_data[v]; uf_data[v] = u; return true; }; graph g(this->size()); for(auto &e : Edges) if(unite(std::get<0>(e), std::get<1>(e))) { g.add_edge(std::get<0>(e), std::get<1>(e), std::get<2>(e)); } return g; } // O(V) std::vector centroid() { int n = size(); std::vector centroid, sz(n); auto dfs = [&](auto self, int now, int per) -> void { sz[now] = 1; bool is_centroid = true; for(auto &e : edges[now]) { if(e.to != per) { self(self, e.to, now); sz[now] += sz[e.to]; if(sz[e.to] > n / 2) is_centroid = false; } } if(n - sz[now] > n / 2) is_centroid = false; if(is_centroid) centroid.push_back(now); }; dfs(dfs, 0, -1); return centroid; } // Ο(V+E) // directed graph from root to leaf graph root_to_leaf(int root = 0) { graph res(size()); std::vector chk(size(), 0); chk[root] = 1; auto dfs = [&](auto self, int now) -> void { for(auto &e : edges[now]) { if(chk[e.to] == 1) continue; chk[e.to] = 1; res.add_edge(now, e.to, e.cost, 1, 0); self(self, e.to); } }; dfs(dfs, root); return res; } // Ο(V+E) // directed graph from leaf to root graph leaf_to_root(int root = 0) { graph res(size()); std::vector chk(size(), 0); chk[root] = 1; auto dfs = [&](auto self, int now) -> void { for(auto &e : edges[now]) { if(chk[e.to] == 1) continue; chk[e.to] = 1; res.add_edge(e.to, now, e.cost, 1, 0); self(self, e.to); } }; dfs(dfs, root); return res; } // long long Chu_Liu_Edmonds(int root = 0) {} }; #line 7 "a.cpp" void main_() { INT(n); using T = tuple; V vec; REP(i, n - 1) { INT(a, b, c); --a, --b; vec.pb(T(c, a, b)); } SORT(vec, >); int c0 = get<0>(vec[0]); debug(c0); auto f = [&](int x) -> bool { graph g(n); //何以上の辺が必要か int lim = c0 - x; vector wei(n); V<> deg(n); int cnt = 0; int root = -1, root2 = -1; for(auto [c, a, b] : vec) { if(c < lim) { if(c > x) return false; continue; } //必ず使うへん if(c > x) { cnt++; root = a, root2 = b; g.add_edge(a, b, 1); } else { g.add_edge(a, b, 0); } } if(root == -1) return true; bool ok = 1; auto dfs = [&](auto dfs, int now, int per) -> int { bool have = 0; int ret = 0; for(auto [to, cost] : g[now]) { if(to == per) continue; int nx = dfs(dfs, to, now) + cost; if(have and nx) { ok = 0; return 0; } if(nx) have = true, ret = nx; } return ret; }; return dfs(dfs, root, root2) + dfs(dfs, root2, root) + 1 == cnt; }; print(bin_search(c0, -1, f)); }