#include using namespace std; #define int long long templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b >; template< typename G > struct StronglyConnectedComponents { const G &g; UnWeightedGraph gg, rg; vector< int > comp, order, used; StronglyConnectedComponents(G &g) : g(g), gg(g.size()), rg(g.size()), comp(g.size(), -1), used(g.size()) { for(int i = 0; i < g.size(); i++) { for(auto e : g[i]) { gg[i].emplace_back((int) e); rg[(int) e].emplace_back(i); } } } int operator[](int k) { return comp[k]; } void dfs(int idx) { if(used[idx]) return; used[idx] = true; for(int to : gg[idx]) dfs(to); order.push_back(idx); } void rdfs(int idx, int cnt) { if(comp[idx] != -1) return; comp[idx] = cnt; for(int to : rg[idx]) rdfs(to, cnt); } void build(UnWeightedGraph &t) { for(int i = 0; i < gg.size(); i++) dfs(i); reverse(begin(order), end(order)); int ptr = 0; for(int i : order) if(comp[i] == -1) rdfs(i, ptr), ptr++; t.resize(ptr); for(int i = 0; i < g.size(); i++) { for(auto &to : g[i]) { int x = comp[i], y = comp[to]; if(x == y) continue; t[x].push_back(y); } } } }; template< typename G > struct LowLink { const G &g; vector< int > used, ord, low; vector< int > articulation; vector< pair< int, int > > bridge; LowLink(const G &g) : g(g) {} int dfs(int idx, int k, int par) { used[idx] = true; ord[idx] = k++; low[idx] = ord[idx]; bool is_articulation = false; int cnt = 0; for(auto &to : g[idx]) { if(!used[to]) { ++cnt; k = dfs(to, k, idx); low[idx] = min(low[idx], low[to]); is_articulation |= ~par && low[to] >= ord[idx]; if(ord[idx] < low[to]) bridge.emplace_back(minmax(idx, (int) to)); } else if(to != par) { low[idx] = min(low[idx], ord[to]); } } is_articulation |= par == -1 && cnt > 1; if(is_articulation) articulation.push_back(idx); return k; } virtual void build() { used.assign(g.size(), 0); ord.assign(g.size(), 0); low.assign(g.size(), 0); int k = 0; for(int i = 0; i < g.size(); i++) { if(!used[i]) k = dfs(i, k, -1); } } }; template< typename G > struct TwoEdgeConnectedComponents : LowLink< G > { using LL = LowLink< G >; vector< int > comp; TwoEdgeConnectedComponents(const G &g) : LL(g) {} int operator[](const int &k) { return comp[k]; } void dfs(int idx, int par, int &k) { if(~par && this->ord[par] >= this->low[idx]) comp[idx] = comp[par]; else comp[idx] = k++; for(auto &to : this->g[idx]) { if(comp[to] == -1) dfs(to, idx, k); } } void build(UnWeightedGraph &t) { LL::build(); comp.assign(this->g.size(), -1); int k = 0; for(int i = 0; i < comp.size(); i++) { if(comp[i] == -1) dfs(i, -1, k); } t.resize(k); for(auto &e : this->bridge) { int x = comp[e.first], y = comp[e.second]; t[x].push_back(y); t[y].push_back(x); } } }; int a[200010]; int b[200010]; int c[200010]; signed main(){ int n, m; cin >> n >> m; UnWeightedGraph graph(n); for(int i = 0;i < m;i++){ cin >> a[i] >> b[i] >> c[i]; a[i]--; b[i]--; if(c[i] == 1){ graph[a[i]].push_back(b[i]); graph[b[i]].push_back(a[i]); } } TwoEdgeConnectedComponents x(graph); UnWeightedGraph tmp, tmp2, tmp3; x.build(tmp); vector cnt(n, 0); for(int i = 0;i < n;i++){ cnt[x[i]]++; if(cnt[x[i]] > 1){ cout << "Yes" << endl; return 0; } } StronglyConnectedComponents scc(graph); scc.build(tmp2); for(int i = 0;i < m;i++){ if(c[i] == 2){ if(scc[a[i]] == scc[b[i]]){ cout << "Yes" << endl; return 0; }else{ tmp2[scc[a[i]]].push_back(scc[b[i]]); } } } StronglyConnectedComponents scc2(tmp2); scc2.build(tmp3); vector cnt2(n, 0); for(int i = 0;i < tmp2.size();i++){ cnt2[scc2[i]]++; if(cnt2[scc2[i]] > 1){ cout << "Yes" << endl; return 0; } } cout << "No" << endl; return 0; }