Submission #1259632

#TimeUsernameProblemLanguageResultExecution timeMemory
1259632nqknhtPotemkin cycle (CEOI15_indcyc)C++20
20 / 100
201 ms91712 KiB
#include <bits/stdc++.h> #define ll long long // CODE NAY KO PHAI DO TOI CODE CHI NOP DE THU TRUONG HOP SAI. Original Author: anha3k25cvp #define dl double #define st first #define nd second #define II pair<int, int> using namespace std; const int N = 1 + 1e3; const int inf = 7 + 1e9; struct Edge { int u, v; }; int s = 0, t = -1; vector<Edge> e; vector<int> deg, vis, p; vector<vector<int>> adj; void dfs(int u) { if (s != 0) return; vis[u] = 1; // cout << u << "\n"; for (int v : adj[u]) { if (!vis[v]) { p[v] = u; // cout << "- " << u << ' ' << v << '\n'; dfs(v); if (s == -1) return; if (s == v) { cout << (v % 2 == 0 ? e[(v / 2)].u : e[(v / 2)].v) << " " ; s = -1; return; } else if (s > 0) { cout << (v % 2 == 0 ? e[(v / 2)].u : e[(v / 2)].v) << " "; return; } } else if (vis[v] == 1) { s = v; // cout << s << "\n"; return; } if (s >= 0) return; } vis[u] = 2; } int main() { #define TASKNAME "" ios_base ::sync_with_stdio(0); cin.tie(0); if (fopen(TASKNAME ".inp", "r")) { freopen(TASKNAME ".inp", "r", stdin); freopen(TASKNAME ".out", "w", stdout); } int n, m; cin >> n >> m; e.resize(2 * m + 2); vector<vector<int>> f(n + 1, vector<int>(n + 1, 0)); for (int i = 1; i <= m; i++) { cin >> e[i].u >> e[i].v; f[e[i].u][e[i].v] = i * 2; f[e[i].v][e[i].u] = i * 2 + 1; } adj.resize(2 * m + 2); for (int i = 1; i <= m; i++) { int u = e[i].u, v = e[i].v; for (int w = 1; w <= n; w++) if (w != u && w != v) { if (f[v][w] && !f[u][w]) adj[i * 2].push_back(f[v][w]); if (f[u][w] && !f[v][w]) adj[i * 2 + 1].push_back(f[u][w]); } } // for (int i = m; i > 0; i--) // { // e[i * 2] = e[i]; // e[i * 2 + 1] = {e[i].v, e[i].u}; // } vis.assign(2 * m + 2, 0); p.assign(2 * m + 2, 0); for (int i = 2; i < m * 2 + 2; i++) if (!vis[i]) { dfs(i); if (s != -1 && s > 0) { cout << (i % 2 == 0 ? e[i / 2].u : e[i / 2].v) << " "; return 0; } if (s != 0) return 0; } if (s == 0) { cout << "no"; return 0; } // vector <int> c; // c.push_back(e[s].u); // while (s != t) { // s = p[s]; // c.push_back(e[s].u); // } // for (int i = (int)c.size() - 1; i >= 0; i --) // for (int j = i + 3; j < c.size(); j ++) // if (f[c[i]][c[j]]) { // for (int u = i; u <= j; u ++) // cout << c[u] << ' '; // return 0; // } return 0; }

Compilation message (stderr)

indcyc.cpp: In function 'int main()':
indcyc.cpp:70:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |         freopen(TASKNAME ".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
indcyc.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen(TASKNAME ".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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