Submission #1193319

#TimeUsernameProblemLanguageResultExecution timeMemory
1193319CrabCNHPipes (CEOI15_pipes)C++20
0 / 100
550 ms7828 KiB
#include <bits/stdc++.h> #define task "BriantheCrab" #define pii pair <int, int> #define fi first #define se second #define szf sizeof #define sz(s) (int)((s).size()) using namespace std; template <class T> void mini (T &t, T f) {if (t > f) t = f;} template <class T> void maxi (T &t, T f) {if (t < f) t = f;} const int maxN = 1e5 + 5; const int maxM = 6e6 + 1; const int mod = 1e9 + 7; mt19937_64 rnd (chrono::steady_clock::now ().time_since_epoch ().count ()); int n, m; int par[maxN], sz[maxN]; int val[maxN]; vector <int> adj[maxN]; void dfs (int u, int p) { for (auto v : adj[u]) { if (v == p) { continue; } dfs (v, u); val[u] += val[v]; if (val[v] == 0) { cout << min (u, v) << ' ' << max (u, v) << '\n'; } } } void init () { for (int i = 1; i <= n; i ++) { sz[i] = 1; par[i] = i; } } int getRoot (int u) { if (par[u] == u) { return u; } return (par[u] = getRoot (par[u])); } void merge (int u, int v) { u = getRoot (u); v = getRoot (v); if (u == v) { return; } if (sz[u] < sz[v]) { swap (u, v); } par[v] = u; sz[u] += sz[v]; adj[u].push_back (v); adj[v].push_back (u); } void solve () { cin >> n >> m; init (); for (int i = 1; i <= m; i ++) { int u, v; cin >> u >> v; if (getRoot (u) == getRoot (v)) { int w = rnd (); val[u] += w; val[v] -= w; } else { merge (u, v); } } for (int i = 1; i <= n; i ++) { if (par[i] == i) { dfs (i, i); } } return; } signed main () { cin.tie (nullptr) -> sync_with_stdio (false); if (fopen (task".inp", "r")) { freopen (task".inp", "r", stdin); freopen (task".out", "w", stdout); } int t = 1; //cin >> t; while (t --) { solve (); } return 0; } // thfdgb

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:95:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   95 |         freopen (task".inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
pipes.cpp:96:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |         freopen (task".out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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