#if !__INCLUDE_LEVEL__ #include __FILE__ class Namori{ public: int V; vector > G, graph; vector deg, loop; vector flag; Namori(int node_size) : V(node_size), G(V), deg(V, 0), flag(V, false){} Namori() : Namori(0){} void add_edge(int u,int v){ G[u].push_back(v), G[v].push_back(u); deg[u]++, deg[v]++; } void dfs(int u){ loop.push_back(u); for(int v : G[u]){ if(flag[v]) continue; flag[v] = true; dfs(v); } } void build(){ graph.resize(V); queue que; // 葉の頂点を que に突っ込む for(int i = 0; i < V; i++){ if(deg[i] == 1){ que.push(i); flag[i] = true; } } // 葉からサイクル上の頂点に向かって登っていく while(!que.empty()){ int p = que.front(); que.pop(); for(int v : G[p]){ if(flag[v]) continue; deg[v]--; //サイクルから端 graph[v].push_back(p); //端からサイクル graph[p].push_back(v); if(deg[v] > 1) continue; que.push(v); flag[v] = true; } } // サイクル上の頂点を loop に格納 for(int i = 0; i < V; i++){ if(flag[i]) continue; flag[i] = true; dfs(i); break; } } }; Namori namo; V loop,col; V

ans; void dfs1(int now,int p=-1){ if(col[now])return ; col[now]=1; for(auto next:namo.G[now]){ if(loop[next])continue; if(p==next)continue; ans.emplace_back(next,now); dfs1(next,now); } return ; } void dfs2(int now,int p){ if(col[now])return ; col[now]=1; for(auto next:namo.G[now]){ if(loop[next]==0)continue; if(p==next)continue; ans.emplace_back(now,next); dfs2(next,now); break; } } struct Solver { void solve() { int n;cin>>n; namo=Namori (n); loop=col=V(n); V

ab; rep(i,n){ int a,b;cin>>a>>b; a--;b--; ab.emplace_back(a,b); namo.add_edge(a,b); } namo.build(); rep(i,sz(namo.loop)){ loop[namo.loop[i]]=1; } rep(i,sz(namo.loop)){ dfs1(namo.loop[i]); } col=V(n); rep(i,n){ if(loop[i]==0)continue; dfs2(i,-1); break; } ans.emplace_back(INF,INF); sort(all(ans)); // cout<"<"< #include using namespace atcoder; // #include // #include // using namespace __gnu_pbds; using namespace std; #define int ll using ll=long long; using ld = long double; using uint = unsigned; using ull = unsigned long long; using P=pair; using TP=tuple; const int INF = 1001001001; const long long INFL = 3e18; const int MAX = 2e6+5; #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 rep(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__) #define rrep(...) overload4(__VA_ARGS__, FOR4_R, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__) #define fore(i,a) for(auto &i:a) #define all(x) x.begin(),x.end() #define allr(x) x.rbegin(),x.rend() #define sz(x) ((int)(x).size()) #define bp(x) (__builtin_popcountll((long long)(x))) #define elif else if #define mpa make_pair #define bit(n) (1LL<<(n)) #define LB(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define UB(c, x) distance((c).begin(), upper_bound(all(c), (x))) template using V = vector; template using max_heap = priority_queue; template using min_heap = priority_queue, greater<>>; templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (bstring join(const T&v,const string& d=""){stringstream s;rep(i,sz(v))(i?s<ostream& operator<<(ostream&o,const vector&v){if(sz(v))o<ostream& operator<<(ostream&o,const pair&v){return o<Tx dup(Tx x, Ty y){return (x+y-1)/y;} templatell suma(const vector&a){ll res(0);for(auto&&x:a)res+=x;return res;} templatell suma(const V>&a){ll res(0);for(auto&&x:a)res+=suma(x);return res;} templatevoid uni(T& a){sort(all(a));a.erase(unique(all(a)),a.end());} templatevoid prepend(vector&a,const T&x){a.insert(a.begin(),x);} templateT vgcd(T m, T n) {return std::gcd(m, n);} templateT vgcd(T a, Args... args) {return vgcd(a, vgcd(args...));} void print(){ putchar(' '); } void print(bool a){ printf("%d", a); } // void print(int a){ printf("%d", a); } void print(unsigned a){ printf("%u", a); } void print(long a){ printf("%ld", a); } void print(long long a){ printf("%lld", a); } void print(unsigned long long a){ printf("%llu", a); } void print(char a){ printf("%c", a); } void print(char *a){ printf("%s", a); } void print(const char *a){ printf("%s", a); } void print(double a){ printf("%.15f", a); } void print(long double a){ printf("%.15Lf", a); } void print(const string& a){ for(auto&& i : a) print(i); } template void print(const complex& a){ if(a.real() >= 0) print('+'); print(a.real()); if(a.imag() >= 0) print('+'); print(a.imag()); print('i'); } template void print(const vector&); template void print(const array&); template void print(const pair& p); template void print(const T (&)[size]); template void print(const vector& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } } template void print(const deque& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } } template void print(const array& a){ print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); print(*i); } } template void print(const pair& p){ print(p.first); putchar(' '); print(p.second); } template void print(const T (&a)[size]){ print(a[0]); for(auto i = a; ++i != end(a); ){ putchar(' '); print(*i); } } template void print(const T& a){ cout << a; } int out(){ putchar('\n'); return 0; } template int out(const T& t){ print(t); putchar('\n'); return 0; } template int out(const Head& head, const Tail&... tail){ print(head); putchar(' '); out(tail...); return 0; } ll binary_search(function 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; } #endif