Submission #782432

#TimeUsernameProblemLanguageResultExecution timeMemory
782432devariaotaNaboj (COCI22_naboj)C++17
0 / 110
382 ms26576 KiB
#include <bits/stdc++.h> #define int long long #define pb push_back #define pii pair<int,int> #define fr first #define sc second using namespace std; const int N = 2e5+5; const int M = 5e5+5; vector<int> adj[N]; vector<int> opp[N]; vector<int> marker; vector<int> par; vector<int> keep; vector<bool> vis; vector<int> v; bool dfs(int x) { marker[x] = 1; for (auto item : adj[x]) { if (!marker[item]) { par[item] = x; if (dfs(item)) return true; } else if (marker[item] == 1) return true; } marker[x] = 2; return false; } void dfs2(int x) { vis[x] = 1; for (auto item : opp[x]) { if (!vis[item] and adj[item].size() and opp[item].size()) dfs(item); } v.push_back(x); } signed main() { int n, m; cin >> n >> m; marker.assign(n+1, 0); par.assign(n+1, -1); vis.assign(n+1, 0); for (int i = 0; i < m; i++) { int a, b; cin >> a >> b; adj[b].pb(a); opp[a].pb(b); } for (int i = 1; i <= n; i++) { if (!marker[i]) { if (dfs(i)) { cout << -1 << endl; return 0; } } } vis.assign(n+1, 0); for (int i = 1; i <= n; i++) if (!vis[i] and adj[i].size() and opp[i].size()) dfs2(i); reverse(v.begin(), v.end()); cout << n << endl; for (auto item : v) { cout << item << " " << 0 << endl; } for (int i = 1; i <= n; i++) { if (!vis[i]) { cout << i << " " << (adj[i].size() == 0) << endl; } } }
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