結果
問題 | No.1424 Ultrapalindrome |
ユーザー | maspy |
提出日時 | 2022-06-06 03:14:17 |
言語 | C++17 (gcc 12.3.0 + boost 1.83.0) |
結果 |
AC
|
実行時間 | 96 ms / 2,000 ms |
コード長 | 22,293 bytes |
コンパイル時間 | 3,115 ms |
コンパイル使用メモリ | 236,020 KB |
実行使用メモリ | 35,364 KB |
最終ジャッジ日時 | 2024-09-21 04:32:58 |
合計ジャッジ時間 | 6,163 ms |
ジャッジサーバーID (参考情報) |
judge4 / judge1 |
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テストケース
テストケース表示入力 | 結果 | 実行時間 実行使用メモリ |
---|---|---|
testcase_00 | AC | 2 ms
6,816 KB |
testcase_01 | AC | 2 ms
6,944 KB |
testcase_02 | AC | 2 ms
6,944 KB |
testcase_03 | AC | 2 ms
6,940 KB |
testcase_04 | AC | 2 ms
6,940 KB |
testcase_05 | AC | 2 ms
6,940 KB |
testcase_06 | AC | 2 ms
6,944 KB |
testcase_07 | AC | 2 ms
6,940 KB |
testcase_08 | AC | 2 ms
6,940 KB |
testcase_09 | AC | 37 ms
14,948 KB |
testcase_10 | AC | 37 ms
15,532 KB |
testcase_11 | AC | 25 ms
11,504 KB |
testcase_12 | AC | 37 ms
14,300 KB |
testcase_13 | AC | 10 ms
6,944 KB |
testcase_14 | AC | 28 ms
12,176 KB |
testcase_15 | AC | 2 ms
6,944 KB |
testcase_16 | AC | 23 ms
10,304 KB |
testcase_17 | AC | 26 ms
11,720 KB |
testcase_18 | AC | 27 ms
11,020 KB |
testcase_19 | AC | 42 ms
14,528 KB |
testcase_20 | AC | 11 ms
6,940 KB |
testcase_21 | AC | 36 ms
13,124 KB |
testcase_22 | AC | 23 ms
9,608 KB |
testcase_23 | AC | 5 ms
6,944 KB |
testcase_24 | AC | 10 ms
6,944 KB |
testcase_25 | AC | 9 ms
6,944 KB |
testcase_26 | AC | 64 ms
17,508 KB |
testcase_27 | AC | 96 ms
24,352 KB |
testcase_28 | AC | 57 ms
35,364 KB |
testcase_29 | AC | 57 ms
35,256 KB |
testcase_30 | AC | 46 ms
24,840 KB |
testcase_31 | AC | 38 ms
24,764 KB |
ソースコード
#line 1 "/home/maspy/compro/library/my_template.hpp" #include <bits/stdc++.h> using namespace std; using ll = long long; using pi = pair<ll, ll>; using vi = vector<ll>; using u32 = unsigned int; using u64 = unsigned long long; using i128 = __int128; template <class T> using vc = vector<T>; template <class T> using vvc = vector<vc<T>>; template <class T> using vvvc = vector<vvc<T>>; template <class T> using vvvvc = vector<vvvc<T>>; template <class T> using vvvvvc = vector<vvvvc<T>>; template <class T> using pq = priority_queue<T>; template <class T> using pqg = priority_queue<T, vector<T>, greater<T>>; #define vec(type, name, ...) vector<type> name(__VA_ARGS__) #define vv(type, name, h, ...) \ vector<vector<type>> name(h, vector<type>(__VA_ARGS__)) #define vvv(type, name, h, w, ...) \ vector<vector<vector<type>>> name( \ h, vector<vector<type>>(w, vector<type>(__VA_ARGS__))) #define vvvv(type, name, a, b, c, ...) \ vector<vector<vector<vector<type>>>> name( \ a, vector<vector<vector<type>>>( \ b, vector<vector<type>>(c, vector<type>(__VA_ARGS__)))) // https://trap.jp/post/1224/ #define FOR1(a) for (ll _ = 0; _ < ll(a); ++_) #define FOR2(i, a) for (ll i = 0; i < ll(a); ++i) #define FOR3(i, a, b) for (ll i = a; i < ll(b); ++i) #define FOR4(i, a, b, c) for (ll i = a; i < ll(b); i += (c)) #define FOR1_R(a) for (ll i = (a)-1; i >= ll(0); --i) #define FOR2_R(i, a) for (ll i = (a)-1; i >= ll(0); --i) #define FOR3_R(i, a, b) for (ll i = (b)-1; i >= ll(a); --i) #define FOR4_R(i, a, b, c) for (ll i = (b)-1; i >= ll(a); i -= (c)) #define overload4(a, b, c, d, e, ...) e #define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__) #define FOR_R(...) \ overload4(__VA_ARGS__, FOR4_R, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__) #define FOR_subset(t, s) for (ll t = s; t >= 0; t = (t == 0 ? -1 : (t - 1) & s)) #define all(x) x.begin(), x.end() #define len(x) ll(x.size()) #define elif else if #define eb emplace_back #define mp make_pair #define mt make_tuple #define fi first #define se second #define stoi stoll template <typename T> T SUM(vector<T> &A) { T sum = T(0); for (auto &&a: A) sum += a; return sum; } #define MIN(v) *min_element(all(v)) #define MAX(v) *max_element(all(v)) #define LB(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define UB(c, x) distance((c).begin(), upper_bound(all(c), (x))) #define UNIQUE(x) sort(all(x)), x.erase(unique(all(x)), x.end()) int popcnt(int x) { return __builtin_popcount(x); } int popcnt(u32 x) { return __builtin_popcount(x); } int popcnt(ll x) { return __builtin_popcountll(x); } int popcnt(u64 x) { return __builtin_popcountll(x); } // (0, 1, 2, 3, 4) -> (-1, 0, 1, 1, 2) int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); } int topbit(u32 x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); } int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); } int topbit(u64 x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); } // (0, 1, 2, 3, 4) -> (-1, 0, 1, 0, 2) int lowbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); } int lowbit(u32 x) { return (x == 0 ? -1 : __builtin_ctz(x)); } int lowbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); } int lowbit(u64 x) { return (x == 0 ? -1 : __builtin_ctzll(x)); } template <typename T, typename U> T ceil(T x, U y) { return (x > 0 ? (x + y - 1) / y : x / y); } template <typename T, typename U> T floor(T x, U y) { return (x > 0 ? x / y : (x - y + 1) / y); } template <typename T, typename U> pair<T, T> divmod(T x, U y) { T q = floor(x, y); return {q, x - q * y}; } ll binary_search(function<bool(ll)> check, ll ok, ll ng) { assert(check(ok)); while (abs(ok - ng) > 1) { auto x = (ng + ok) / 2; if (check(x)) ok = x; else ng = x; } return ok; } template <class T, class S> inline bool chmax(T &a, const S &b) { return (a < b ? a = b, 1 : 0); } template <class T, class S> inline bool chmin(T &a, const S &b) { return (a > b ? a = b, 1 : 0); } vi s_to_vi(const string &S, char first_char) { vi A(S.size()); FOR(i, S.size()) { A[i] = S[i] - first_char; } return A; } template <typename T> vector<T> cumsum(vector<T> &A, int off = 1) { int N = A.size(); vector<T> B(N + 1); FOR(i, N) { B[i + 1] = B[i] + A[i]; } if (off == 0) B.erase(B.begin()); return B; } template <typename CNT, typename T> vc<CNT> bincount(const vc<T> &A, int size) { vc<CNT> C(size); for (auto &&x: A) { ++C[x]; } return C; } template <typename T> vector<int> argsort(const vector<T> &A) { // stable vector<int> ids(A.size()); iota(all(ids), 0); sort(all(ids), [&](int i, int j) { return A[i] < A[j] || (A[i] == A[j] && i < j); }); return ids; } // A[I[0]], A[I[1]], ... template <typename T> vc<T> rearrange(const vc<T> &A, const vc<int> &I) { int n = len(A); assert(len(I) == n); vc<T> B(n); FOR(i, n) B[i] = A[I[i]]; return B; } #line 1 "/home/maspy/compro/library/other/io.hpp" // based on yosupo's fastio #include <unistd.h> namespace detail { template <typename T, decltype(&T::is_modint) = &T::is_modint> std::true_type check_value(int); template <typename T> std::false_type check_value(long); } // namespace detail template <typename T> struct is_modint : decltype(detail::check_value<T>(0)) {}; template <typename T> using is_modint_t = enable_if_t<is_modint<T>::value>; template <typename T> using is_not_modint_t = enable_if_t<!is_modint<T>::value>; struct Scanner { FILE *fp; char line[(1 << 15) + 1]; size_t st = 0, ed = 0; void reread() { memmove(line, line + st, ed - st); ed -= st; st = 0; ed += fread(line + ed, 1, (1 << 15) - ed, fp); line[ed] = '\0'; } bool succ() { while (true) { if (st == ed) { reread(); if (st == ed) return false; } while (st != ed && isspace(line[st])) st++; if (st != ed) break; } if (ed - st <= 50) { bool sep = false; for (size_t i = st; i < ed; i++) { if (isspace(line[i])) { sep = true; break; } } if (!sep) reread(); } return true; } template <class T, enable_if_t<is_same<T, string>::value, int> = 0> bool read_single(T &ref) { if (!succ()) return false; while (true) { size_t sz = 0; while (st + sz < ed && !isspace(line[st + sz])) sz++; ref.append(line + st, sz); st += sz; if (!sz || st != ed) break; reread(); } return true; } template <class T, enable_if_t<is_integral<T>::value, int> = 0> bool read_single(T &ref) { if (!succ()) return false; bool neg = false; if (line[st] == '-') { neg = true; st++; } ref = T(0); while (isdigit(line[st])) { ref = 10 * ref + (line[st++] & 0xf); } if (neg) ref = -ref; return true; } template <class T, is_modint_t<T> * = nullptr> bool read_single(T &ref) { long long val = 0; bool f = read_single(val); ref = T(val); return f; } bool read_single(double &ref) { string s; if (!read_single(s)) return false; ref = std::stod(s); return true; } bool read_single(char &ref) { string s; if (!read_single(s) || s.size() != 1) return false; ref = s[0]; return true; } template <class T> bool read_single(vector<T> &ref) { for (auto &d: ref) { if (!read_single(d)) return false; } return true; } template <class T, class U> bool read_single(pair<T, U> &p) { return (read_single(p.first) && read_single(p.second)); } template <class A, class B, class C> bool read_single(tuple<A, B, C> &p) { return (read_single(get<0>(p)) && read_single(get<1>(p)) && read_single(get<2>(p))); } template <class A, class B, class C, class D> bool read_single(tuple<A, B, C, D> &p) { return (read_single(get<0>(p)) && read_single(get<1>(p)) && read_single(get<2>(p)) && read_single(get<3>(p))); } void read() {} template <class H, class... T> void read(H &h, T &... t) { bool f = read_single(h); assert(f); read(t...); } Scanner(FILE *fp) : fp(fp) {} }; struct Printer { Printer(FILE *_fp) : fp(_fp) {} ~Printer() { flush(); } static constexpr size_t SIZE = 1 << 15; FILE *fp; char line[SIZE], small[50]; size_t pos = 0; void flush() { fwrite(line, 1, pos, fp); pos = 0; } void write(const char &val) { if (pos == SIZE) flush(); line[pos++] = val; } template <class T, enable_if_t<is_integral<T>::value, int> = 0> void write(T val) { if (pos > (1 << 15) - 50) flush(); if (val == 0) { write('0'); return; } if (val < 0) { write('-'); val = -val; // todo min } size_t len = 0; while (val) { small[len++] = char(0x30 | (val % 10)); val /= 10; } for (size_t i = 0; i < len; i++) { line[pos + i] = small[len - 1 - i]; } pos += len; } void write(const string &s) { for (char c: s) write(c); } void write(const char *s) { size_t len = strlen(s); for (size_t i = 0; i < len; i++) write(s[i]); } void write(const double &x) { ostringstream oss; oss << setprecision(15) << x; string s = oss.str(); write(s); } void write(const long double &x) { ostringstream oss; oss << setprecision(15) << x; string s = oss.str(); write(s); } template <class T, is_modint_t<T> * = nullptr> void write(T &ref) { write(ref.val); } template <class T> void write(const vector<T> &val) { auto n = val.size(); for (size_t i = 0; i < n; i++) { if (i) write(' '); write(val[i]); } } template <class T, class U> void write(const pair<T, U> &val) { write(val.first); write(' '); write(val.second); } template <class A, class B, class C> void write(const tuple<A, B, C> &val) { auto &[a, b, c] = val; write(a), write(' '), write(b), write(' '), write(c); } template <class A, class B, class C, class D> void write(const tuple<A, B, C, D> &val) { auto &[a, b, c, d] = val; write(a), write(' '), write(b), write(' '), write(c), write(' '), write(d); } template <class A, class B, class C, class D, class E> void write(const tuple<A, B, C, D, E> &val) { auto &[a, b, c, d, e] = val; write(a), write(' '), write(b), write(' '), write(c), write(' '), write(d), write(' '), write(e); } template <class A, class B, class C, class D, class E, class F> void write(const tuple<A, B, C, D, E, F> &val) { auto &[a, b, c, d, e, f] = val; write(a), write(' '), write(b), write(' '), write(c), write(' '), write(d), write(' '), write(e), write(' '), write(f); } template <class T, size_t S> void write(const array<T, S> &val) { auto n = val.size(); for (size_t i = 0; i < n; i++) { if (i) write(' '); write(val[i]); } } void write(i128 val) { string s; bool negative = 0; if(val < 0){ negative = 1; val = -val; } while (val) { s += '0' + int(val % 10); val /= 10; } if(negative) s += "-"; reverse(all(s)); if (len(s) == 0) s = "0"; write(s); } }; Scanner scanner = Scanner(stdin); Printer printer = Printer(stdout); void flush() { printer.flush(); } void print() { printer.write('\n'); } template <class Head, class... Tail> void print(Head &&head, Tail &&... tail) { printer.write(head); if (sizeof...(Tail)) printer.write(' '); print(forward<Tail>(tail)...); } void read() {} template <class Head, class... Tail> void read(Head &head, Tail &... tail) { scanner.read(head); read(tail...); } #define INT(...) \ int __VA_ARGS__; \ read(__VA_ARGS__) #define LL(...) \ ll __VA_ARGS__; \ read(__VA_ARGS__) #define STR(...) \ string __VA_ARGS__; \ read(__VA_ARGS__) #define CHAR(...) \ char __VA_ARGS__; \ read(__VA_ARGS__) #define DBL(...) \ double __VA_ARGS__; \ read(__VA_ARGS__) #define VEC(type, name, size) \ vector<type> name(size); \ read(name) #define VV(type, name, h, w) \ vector<vector<type>> name(h, vector<type>(w)); \ read(name) void YES(bool t = 1) { print(t ? "YES" : "NO"); } void NO(bool t = 1) { YES(!t); } void Yes(bool t = 1) { print(t ? "Yes" : "No"); } void No(bool t = 1) { Yes(!t); } void yes(bool t = 1) { print(t ? "yes" : "no"); } void no(bool t = 1) { yes(!t); } #line 2 "/home/maspy/compro/library/graph/base.hpp" template <typename T> struct Edge { int frm, to; T cost; int id; }; template <typename T = int, bool directed = false> struct Graph { int N, M; using cost_type = T; using edge_type = Edge<T>; vector<edge_type> edges; vector<int> indptr; vector<edge_type> csr_edges; bool prepared; class OutgoingEdges { public: OutgoingEdges(const Graph* G, int l, int r) : G(G), l(l), r(r) {} const edge_type* begin() const { if (l == r) { return 0; } return &G->csr_edges[l]; } const edge_type* end() const { if (l == r) { return 0; } return &G->csr_edges[r]; } private: int l, r; const Graph* G; }; bool is_prepared() { return prepared; } constexpr bool is_directed() { return directed; } Graph() : N(0), M(0), prepared(0) {} Graph(int N) : N(N), M(0), prepared(0) {} void add(int frm, int to, T cost = 1, int i = -1) { assert(!prepared); assert(0 <= frm && 0 <= to && to < N); if (i == -1) i = M; auto e = edge_type({frm, to, cost, i}); edges.eb(e); ++M; } // wt, off void read_tree(bool wt = false, int off = 1) { read_graph(N - 1, wt, off); } void read_graph(int M, bool wt = false, int off = 1) { FOR(M) { INT(a, b); a -= off, b -= off; if (!wt) { add(a, b); } else { T c; read(c); add(a, b, c); } } build(); } void read_parent(int off = 1) { FOR3(v, 1, N) { INT(p); p -= off; add(p, v); } build(); } void build() { assert(!prepared); prepared = true; indptr.assign(N + 1, 0); for (auto&& e: edges) { indptr[e.frm + 1]++; if (!directed) indptr[e.to + 1]++; } FOR(v, N) indptr[v + 1] += indptr[v]; auto counter = indptr; csr_edges.resize(indptr.back() + 1); for (auto&& e: edges) { csr_edges[counter[e.frm]++] = e; if (!directed) csr_edges[counter[e.to]++] = edge_type({e.to, e.frm, e.cost, e.id}); } } OutgoingEdges operator[](int v) const { assert(prepared); return {this, indptr[v], indptr[v + 1]}; } void debug() { print("Graph"); if (!prepared) { print("frm to cost id"); for (auto&& e: edges) print(e.frm, e.to, e.cost, e.id); } else { print("indptr", indptr); print("frm to cost id"); FOR(v, N) for (auto&& e: (*this)[v]) print(e.frm, e.to, e.cost, e.id); } } }; #line 3 "/home/maspy/compro/library/graph/bfs01.hpp" template <typename Graph> pair<vc<ll>, vc<int>> bfs01(Graph& G, ll v) { assert(G.is_prepared()); int N = G.N; vc<ll> dist(N, -1); vc<int> par(N, -1); deque<int> que; dist[v] = 0; que.push_front(v); while (!que.empty()) { auto v = que.front(); que.pop_front(); for (auto&& e: G[v]) { if (dist[e.to] == -1 || dist[e.to] > dist[e.frm] + e.cost) { dist[e.to] = dist[e.frm] + e.cost; par[e.to] = e.frm; if (e.cost == 0) que.push_front(e.to); else que.push_back(e.to); } } } return {dist, par}; } // 多点スタート。[dist, par, root] template <typename Graph> tuple<vc<ll>, vc<int>, vc<int>> bfs01(Graph& G, vc<int> vs) { assert(G.is_prepared()); int N = G.N; vc<ll> dist(N, -1); vc<int> par(N, -1); vc<int> root(N, -1); deque<int> que; for (auto&& v: vs) { dist[v] = 0; root[v] = v; que.push_front(v); } while (!que.empty()) { auto v = que.front(); que.pop_front(); for (auto&& e: G[v]) { if (dist[e.to] == -1 || dist[e.to] > dist[e.frm] + e.cost) { dist[e.to] = dist[e.frm] + e.cost; root[e.to] = root[e.frm]; par[e.to] = e.frm; if (e.cost == 0) que.push_front(e.to); else que.push_back(e.to); } } } return {dist, par, root}; } #line 1 "/home/maspy/compro/library/graph/restore_path.hpp" vector<int> restore_path(vector<int> par, int t){ vector<int> pth = {t}; while (par[pth.back()] != -1) pth.eb(par[pth.back()]); reverse(all(pth)); return pth; } #line 3 "/home/maspy/compro/library/graph/tree_diameter.hpp" template <typename T> pair<T, vc<int>> tree_diameter(Graph<T>& G) { assert(G.is_prepared()); int A, B; { auto [dist, par] = bfs01(G, 0); A = max_element(all(dist)) - dist.begin(); } auto [dist, par] = bfs01(G, A); B = max_element(all(dist)) - dist.begin(); vc<int> P = restore_path(par, B); return {dist[B], P}; } #line 2 "/home/maspy/compro/library/graph/degree.hpp" template <typename Graph> vector<int> degree(Graph& G) { vector<int> deg(G.N); for(auto&& e : G.edges) deg[e.frm]++, deg[e.to]++; return deg; } template <typename Graph> pair<vector<int>, vector<int>> degree_inout(Graph& G) { vector<int> indeg(G.N), outdeg(G.N); for (auto&& e: G.edges) { indeg[e.to]++, outdeg[e.frm]++; } return {indeg, outdeg}; } #line 3 "/home/maspy/compro/library/graph/hld.hpp" /* HL分解。O(N) 時間構築。 LCA, LA などは O(logN) 時間。 木以外、非連結でも使えるようにした。dfs順序や親がとれる。 */ template <typename Graph> struct HLD { Graph &G; using Graph_type = Graph; using WT = typename Graph::cost_type; int N; vector<int> LID, RID, head, V, parent, root; vc<int> depth; vc<WT> depth_weighted; vector<bool> in_tree; HLD(Graph &G, int r = -1) : G(G), N(G.N), LID(G.N), RID(G.N), head(G.N, r), V(G.N), parent(G.N, -1), depth(G.N, -1), depth_weighted(G.N, 0), root(G.N, -1), in_tree(G.M, 0) { assert(G.is_prepared()); int t1 = 0; if (r != -1) { dfs_sz(r, -1); dfs_hld(r, t1); } else { FOR(r, N) if (parent[r] == -1) { head[r] = r; dfs_sz(r, -1); dfs_hld(r, t1); } } for (auto &&v: V) root[v] = (parent[v] == -1 ? v : root[parent[v]]); } void dfs_sz(int v, int p) { auto &sz = RID; parent[v] = p; depth[v] = (p == -1 ? 0 : depth[p] + 1); sz[v] = 1; int l = G.indptr[v], r = G.indptr[v + 1]; auto &csr = G.csr_edges; // 使う辺があれば先頭にする FOR3_R(i, l, r - 1) { if (depth[csr[i + 1].to] == -1) swap(csr[i], csr[i + 1]); } int hld_sz = 0; for (int i = l; i < r; ++i) { auto e = csr[i]; if (depth[e.to] != -1) continue; in_tree[e.id] = 1; depth_weighted[e.to] = depth_weighted[v] + e.cost; dfs_sz(e.to, v); sz[v] += sz[e.to]; if (chmax(hld_sz, sz[e.to]) && l < i) { swap(csr[l], csr[i]); } } } void dfs_hld(int v, int ×) { LID[v] = times++; RID[v] += LID[v]; V[LID[v]] = v; bool heavy = true; for (auto &&e: G[v]) { if (!in_tree[e.id] || depth[e.to] <= depth[v]) continue; head[e.to] = (heavy ? head[v] : e.to); heavy = false; dfs_hld(e.to, times); } } int e_to_v(int eid) { auto e = G.edges[eid]; return (parent[e.frm] == e.to ? e.frm : e.to); } int ELID(int v) { return 2 * LID[v] - depth[v]; } int ERID(int v) { return 2 * RID[v] - depth[v] - 1; } /* k: 0-indexed */ int LA(int v, int k) { while (1) { int u = head[v]; if (LID[v] - k >= LID[u]) return V[LID[v] - k]; k -= LID[v] - LID[u] + 1; v = parent[u]; } } int LCA(int u, int v) { for (;; v = parent[head[v]]) { if (LID[u] > LID[v]) swap(u, v); if (head[u] == head[v]) return u; } } int lca(int u, int v) { return LCA(u, v); } int la(int u, int v) { return LA(u, v); } int subtree_size(int v) { return RID[v] - LID[v]; } int dist(int a, int b) { int c = LCA(a, b); return depth[a] + depth[b] - 2 * depth[c]; } WT dist(int a, int b, bool weighted) { assert(weighted); int c = LCA(a, b); return depth_weighted[a] + depth_weighted[b] - 2 * depth_weighted[c]; } bool in_subtree(int a, int b) { return LID[b] <= LID[a] && LID[a] < RID[b]; } int move(int a, int b) { assert(a != b); return (in_subtree(b, a) ? LA(b, depth[b] - depth[a] - 1) : parent[a]); } vc<int> collect_child(int v) { vc<int> res; for (auto &&e: G[v]) if (e.to != parent[v]) res.eb(e.to); return res; } vc<pair<int, int>> get_path_decomposition(int u, int v, bool edge) { // [始点, 終点] の"閉"区間列。 vc<pair<int, int>> up, down; while (1) { if (head[u] == head[v]) break; if (LID[u] < LID[v]) { down.eb(LID[head[v]], LID[v]); v = parent[head[v]]; } else { up.eb(LID[u], LID[head[u]]); u = parent[head[u]]; } } if (LID[u] < LID[v]) down.eb(LID[u] + edge, LID[v]); elif (LID[v] + edge <= LID[u]) up.eb(LID[u], LID[v] + edge); reverse(all(down)); up.insert(up.end(), all(down)); return up; } void debug() { print("V", V); print("LID", LID); print("RID", RID); print("parent", parent); print("depth", depth); print("head", head); print("in_tree(edge)", in_tree); print("root", root); } }; #line 7 "main.cpp" void solve() { LL(N); Graph G(N + N - 1); FOR(e, N, N + N - 1) { LL(a, b); --a, --b; G.add(e, a); G.add(e, b); } G.build(); auto [diam, P] = tree_diameter(G); int r = P[len(P) / 2]; auto dist = bfs01(G, r).fi; vi V; vi A; auto deg = degree(G); FOR(v, G.N) if (deg[v] == 1) A.eb(dist[v]), V.eb(v); if (MAX(A) != MIN(A)) return No(); HLD hld(G, r); sort(all(V), [&](auto& x, auto& y) { return hld.LID[x] < hld.LID[y]; }); FOR(i, len(V) - 1) { ll a = V[i], b = V[i + 1]; if (hld.LCA(a, b) != r) return No(); } Yes(); } signed main() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); ll T = 1; // LL(T); FOR(T) solve(); return 0; }