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  1. #include <iostream>
  2. #include <queue>
  3. #include <vector>
  4. #include<algorithm>
  5. using namespace std;
  6.  
  7. bool valid;
  8. void dfs(int node, vector<vector<int>> & graph, vector<int> & color){
  9.     for(int child : graph[node]){
  10.         if(color[node] == color[child])
  11.             valid = false;
  12.  
  13.         if(color[child] == -1){
  14.             color[child] = !color[node];
  15.             dfs(child, graph, color);
  16.         }
  17.     }
  18.  
  19.  
  20.  
  21. }
  22. int main(){
  23.  
  24.     int nodes, from, to;
  25.  
  26.     while(cin >> nodes){
  27.         valid = true;
  28.         if(nodes == 0)
  29.             break;
  30.         vector<vector<int>> graph(nodes + 1);
  31.         vector<int> color(nodes + 1, -1);
  32.  
  33.         while(cin >> from >> to){
  34.             if(from == 0 && to == 0)
  35.                 break;
  36.  
  37.             graph[from].push_back(to);
  38.             graph[to].push_back(from);
  39.  
  40.         }
  41.         for(int node = 1; node <= nodes; ++node){
  42.             if(color[node] == -1){
  43.                 color[node] = 1;
  44.                 dfs(node, graph, color);
  45.             }
  46.         }
  47.         if(valid)
  48.             cout <<"YES\n";
  49.         else 
  50.             cout <<"NO\n";
  51.     }
  52.  
  53. /* */
  54. }
Success #stdin #stdout 0s 4508KB
comments (?)
stdin
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4
1 2
1 3
1 4
2 3
2 4
3 4
0 0
6
1 2
1 3
1 6
2 3
2 5
3 4
4 5
4 6
5 6
0 0
0
stdout
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NO
NO
https://ideone.com/pWyN1a
language:
C++14 (clang 8.0)
created:
4 years ago
visibility:
secret

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