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#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_3_A" #include "../../template.h" #include "../DfsTree/BridgeArticulation.h" void solve() { int n, m; cin >> n >> m; vector<vector<int>> g(n); REP(i,m) { int u, v; cin >> u >> v; g[u].push_back(v); g[v].push_back(u); } UndirectedDfs tree(g); auto res = tree.articulation_points; sort(res.begin(), res.end()); for (int r : res) cout << r << '\n'; }
#line 1 "Graph/tests/aizu_grl_3_a_articulation_points.test.cpp" #define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_3_A" #line 1 "template.h" #include <bits/stdc++.h> using namespace std; #define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++) #define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--) #define REP(i,a) for(int i=0,_a=(a); i<_a; i++) #define EACH(it,a) for(__typeof(a.begin()) it = a.begin(); it != a.end(); ++it) #define DEBUG(x) { cout << #x << " = "; cout << (x) << endl; } #define PR(a,n) { cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl; } #define PR0(a,n) { cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl; } #define sqr(x) ((x) * (x)) // For printing pair, container, etc. // Copied from https://quangloc99.github.io/2021/07/30/my-CP-debugging-template.html template<class U, class V> ostream& operator << (ostream& out, const pair<U, V>& p) { return out << '(' << p.first << ", " << p.second << ')'; } template<class Con, class = decltype(begin(declval<Con>()))> typename enable_if<!is_same<Con, string>::value, ostream&>::type operator << (ostream& out, const Con& con) { out << '{'; for (auto beg = con.begin(), it = beg; it != con.end(); it++) { out << (it == beg ? "" : ", ") << *it; } return out << '}'; } template<size_t i, class T> ostream& print_tuple_utils(ostream& out, const T& tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); } template<class ...U> ostream& operator << (ostream& out, const tuple<U...>& t) { return print_tuple_utils<0, tuple<U...>>(out, t); } mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count()); long long get_rand(long long r) { return uniform_int_distribution<long long> (0, r-1)(rng); } template<typename T> vector<T> read_vector(int n) { vector<T> res(n); for (int& x : res) cin >> x; return res; } void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); solve(); return 0; } #line 1 "Graph/DfsTree/BridgeArticulation.h" // UndirectedDFS, for finding bridges & articulation points {{{ // Assume already have undirected graph vector< vector<int> > G with V vertices // Vertex index from 0 // Usage: // UndirectedDfs tree; // Then you can use tree.bridges and tree.articulation_points // // Tested: // - https://judge.yosupo.jp/problem/two_edge_connected_components struct UndirectedDfs { vector<vector<int>> g; int n; vector<int> low, num, parent; vector<bool> is_articulation; int counter, root, children; vector< pair<int,int> > bridges; vector<int> articulation_points; map<pair<int,int>, int> cnt_edges; UndirectedDfs(const vector<vector<int>>& _g) : g(_g), n(g.size()), low(n, 0), num(n, -1), parent(n, 0), is_articulation(n, false), counter(0), children(0) { for (int u = 0; u < n; u++) { for (int v : g[u]) { cnt_edges[{u, v}] += 1; } } for(int i = 0; i < n; ++i) if (num[i] == -1) { root = i; children = 0; dfs(i); is_articulation[root] = (children > 1); } for(int i = 0; i < n; ++i) if (is_articulation[i]) articulation_points.push_back(i); } private: void dfs(int u) { low[u] = num[u] = counter++; for (int v : g[u]) { if (num[v] == -1) { parent[v] = u; if (u == root) children++; dfs(v); if (low[v] >= num[u]) is_articulation[u] = true; if (low[v] > num[u]) { if (cnt_edges[{u, v}] == 1) { bridges.push_back(make_pair(u, v)); } } low[u] = min(low[u], low[v]); } else if (v != parent[u]) low[u] = min(low[u], num[v]); } } }; // }}} #line 5 "Graph/tests/aizu_grl_3_a_articulation_points.test.cpp" void solve() { int n, m; cin >> n >> m; vector<vector<int>> g(n); REP(i,m) { int u, v; cin >> u >> v; g[u].push_back(v); g[v].push_back(u); } UndirectedDfs tree(g); auto res = tree.articulation_points; sort(res.begin(), res.end()); for (int r : res) cout << r << '\n'; }