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#define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_4_A" #include "../../template.h" #include "../DfsTree/StronglyConnected.h" void solve() { int n, m; cin >> n >> m; vector<vector<int>> g(n); while (m--) { int u, v; cin >> u >> v; g[u].push_back(v); } DirectedDfs tree(g); for (auto comp : tree.scc) { if (comp.size() > 1) { cout << 1 << endl; return; } } cout << 0 << endl; }
#line 1 "Graph/tests/aizu_grl_4_a_strongly_connected_cycle_check.test.cpp" #define PROBLEM "https://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=GRL_4_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/StronglyConnected.h" // Index from 0 // Usage: // DirectedDfs tree; // Now you can use tree.scc // // Note: reverse(tree.scc) is topo sorted // // Tested: // - (requires scc to be topo sorted) https://judge.yosupo.jp/problem/scc // - https://cses.fi/problemset/task/1686/ // - (edges have costs) https://oj.vnoi.info/problem/bedao_g16_b struct DirectedDfs { vector<vector<int>> g; int n; vector<int> num, low, current, S; int counter; vector<int> comp_ids; vector< vector<int> > scc; DirectedDfs(const vector<vector<int>>& _g) : g(_g), n(g.size()), num(n, -1), low(n, 0), current(n, 0), counter(0), comp_ids(n, -1) { for (int i = 0; i < n; i++) { if (num[i] == -1) dfs(i); } } void dfs(int u) { low[u] = num[u] = counter++; S.push_back(u); current[u] = 1; for (auto v : g[u]) { if (num[v] == -1) dfs(v); if (current[v]) low[u] = min(low[u], low[v]); } if (low[u] == num[u]) { scc.push_back(vector<int>()); while (1) { int v = S.back(); S.pop_back(); current[v] = 0; scc.back().push_back(v); comp_ids[v] = ((int) scc.size()) - 1; if (u == v) break; } } } // build DAG of strongly connected components // Returns: adjacency list of DAG std::vector<std::vector<int>> build_scc_dag() { std::vector<std::vector<int>> dag(scc.size()); for (int u = 0; u < n; u++) { int x = comp_ids[u]; for (int v : g[u]) { int y = comp_ids[v]; if (x != y) { dag[x].push_back(y); } } } return dag; } }; #line 5 "Graph/tests/aizu_grl_4_a_strongly_connected_cycle_check.test.cpp" void solve() { int n, m; cin >> n >> m; vector<vector<int>> g(n); while (m--) { int u, v; cin >> u >> v; g[u].push_back(v); } DirectedDfs tree(g); for (auto comp : tree.scc) { if (comp.size() > 1) { cout << 1 << endl; return; } } cout << 0 << endl; }