Submission #1024921

#	Time	Username	Problem	Language	Result	Execution time	Memory
1024921		gs25	Untitled (POI11_kon)	C++17	0 / 100	839 ms	72752 KiB

Main

#include <bits/stdc++.h>

using namespace std; 

const int MAXN = 5010; 

bool adj[MAXN][MAXN]; 
int scc[MAXN]; 
int deg[MAXN]; 
int n; 

/*
if(adj[i][j]==0){
        g[i].push_back(j+n); 
        rg[j+n].push_back(i); 
      }
      else{
        g[i+n].push_back(j); 
        rg[j].push_back(i+n); 
      }
*/

bool vis[MAXN*2]; 
stack<int> st; 
void dfs(int i){
  if(vis[i]) return; 
  vis[i] = 1; 
  if(i<=n){
    for(int j=1; j<=n; j++) if(j!=i && adj[i][j]==0 && !vis[j+n]) dfs(j+n); 
  }
  else {
    for(int j=1; j<=n; j++) if(j!=i && adj[i-n][j]==1 && !vis[j]) dfs(j); 
  }
  /*
  for(auto ne:g[i]){
    if(!vis[ne]) dfs(ne); 
  }
  */
  
  st.push(i); 
}

void dfs1(int i, int pv){
  if(vis[i]) return; 
  vis[i] = 1; 
  scc[i] = pv; 
  if(i<=n){
    for(int j=1; j<=n; j++) if(j!=i && adj[i][j] && !vis[j+n]) dfs(j+n); 
  }
  else {
    for(int j=1; j<=n; j++) if(j!=i && !adj[i-n][j] && !vis[j]) dfs(j); 
  }
  /*
  for(auto ne:rg[i]){
    if(!vis[ne]) dfs1(ne,pv); 
  }
  */
  
}

int main(void){
  ios_base::sync_with_stdio(false); 
  cin.tie(nullptr); 
  cout.tie(nullptr); 
  cin >> n; 
  int a = 0; 
  for(int i=1; i<=n; i++){
    int x; cin >> x; a+=x; 
    while(x--){
      int j; cin >> j; adj[i][j] = 1; 
    }
  }
  if(a==0 || a== n*(n+1)){
    cout << n; return 0; 
  }
  /*
  for(int i=1; i<=n; i++){
    for(int j=1; j<=n; j++){
      if(j==i) continue; 
      if(adj[i][j]==0){
        g[i].push_back(j+n); 
        rg[j+n].push_back(i); 
      }
      else{
        g[i+n].push_back(j); 
        rg[j].push_back(i+n); 
      }
    }
  }
  */
  
  for(int i=1; i<=n*2; i++) if(!vis[i]) dfs(i); 
  for(int i=1; i<=n*2; i++) vis[i] = 0; 
  int pv = 0; 
  while(!st.empty()){
    int t = st.top(); st.pop(); if(!vis[t]) dfs1(t,pv++); 
  }
  vector<int> c, nc; 
  for(int i=1; i<=n; i++){
    if(scc[i]==scc[i+n]) {
      cout << 0; return 0; 
    }
    if(scc[i]<scc[i+n]) nc.push_back(i); 
    else c.push_back(i); 
  }
  assert(c.size()!=0 && nc.size()!=0); 
  //for(auto x : c) cerr << x << " "; 
  for(auto x : c){
    for(auto y : nc){
      if(adj[x][y]) deg[x]++, deg[y]++; 
    }
  }
  int ans = 1; 
  for(auto n : c) if(deg[n]==0) ans++; 
  for(auto n : nc) if(deg[n]==c.size()) ans++; 
  for(auto n : c){
    for(auto nn : nc){
      int p = deg[n] - adj[n][nn], q = deg[nn] - adj[n][nn]; 
      if(p==0 && q==c.size()-1) ans++; 
    }
  }
  cout << ans;
}

Compilation message (stderr)

kon.cpp: In function 'int main()':
kon.cpp:115:29: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  115 |   for(auto n : nc) if(deg[n]==c.size()) ans++;
      |                       ~~~~~~^~~~~~~~~~
kon.cpp:119:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  119 |       if(p==0 && q==c.size()-1) ans++;
      |                  ~^~~~~~~~~~~~

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