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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int m,n;
  5.  
  6. void dfs1(vector<int>*g,int u,stack<int>&s,vector<int>&vis)
  7. {
  8.  
  9.     vis[u]=1;
  10.     for(int x:g[u])
  11.     {
  12.         if(vis[x]==1) continue;
  13.         dfs1(g,x,s,vis);
  14.     }
  15.     vis[u]=2;
  16.     s.push(u);
  17. }
  18.  
  19. void dfs2(vector<int>*g,int u,vector<int>&vis,vector<int>&scc)
  20. {
  21.  
  22.     vis[u]=1;
  23.     scc.push_back(u);
  24.     for(int x:g[u])
  25.     {
  26.         if(vis[x]==1) continue;
  27.         dfs2(g,x,vis,scc);
  28.     }
  29.     vis[u]=2;
  30.  
  31. }
  32.  
  33. int main()
  34. {
  35.     cin>>n>>m;
  36.     vector<int>g1[n+1],g2[n+1];
  37.  
  38.      for(int i=0;i<m;i++)
  39.     {
  40.         int u,v;
  41.         cin>>u>>v;
  42.  
  43.         g1[u].push_back(v);
  44.         g2[v].push_back(u);
  45.     }
  46.  
  47.     stack<int>s;
  48.     vector<int>vis(n+1,0);
  49.     for(int i=1;i<=n;i++)
  50.     {
  51.         if(vis[i]==0)
  52.         {
  53.             dfs1(g1,i,s,vis);
  54.         }
  55.     }
  56.     vector<int>vis2(n+1,0);
  57.     vector<vector<int>>allscc;
  58.     while(!s.empty())
  59.  
  60.     {
  61.         int cur=s.top();
  62.         s.pop();
  63.         if(vis2[cur]==0)
  64.         {
  65.             vector<int>scc;
  66.             dfs2(g2,cur,vis2,scc);
  67.             allscc.push_back(scc);
  68.         }
  69.     }
  70.     for(auto x: allscc)
  71.     {
  72.         for(int u:x)
  73.         {
  74.             cout<<u<< " ";
  75.         }
  76.         cout<<endl;
  77.     }
  78.  
  79. }
  80. /*
  81.  
  82. 8 14
  83. 1 2
  84. 2 3
  85. 3 1
  86. 3 4
  87. 2 4
  88. 2 5
  89. 4 6
  90. 6 4
  91. 5 7
  92. 7 5
  93. 5 6
  94. 6 8
  95. 7 8
  96. 8 8
  97. */
  98.  
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/WVGHSv
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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