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  1. #include<bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define ll long long 
  6. vector<int>adj[1000001];
  7. // vector<int>cc(1000001,0);
  8. int cc[1000001];
  9. int cc_cnt;
  10. bool vis[1000001];
  11. void dfs(int x){
  12. 	vis[x] = true;
  13. 	cc[x] = cc_cnt;
  14. 	for(int neigh:adj[x])
  15. 		if(!vis[neigh])
  16. 			{dfs(neigh);}
  17. }
  18.  
  19. int main(){
  20. 	int t;
  21. 	cin>>t;
  22. 	ios_base::sync_with_stdio(false);
  23. 	cin.tie(NULL);
  24. 	while(t--){
  25. 		int n,k;
  26. 		cin>>n>>k;
  27. 		bool flag = 1;
  28. 		vector<pair<int,int>>queries;			
  29. 		for(int i=0;i<=n;i++){
  30. 			vis[i] = 0;
  31. 			adj[i].clear();
  32.             cc[i]=0;
  33. 			}
  34. 		cc_cnt =0;
  35. 		while(k--){
  36. 			int x1,x2;
  37. 			string op;
  38. 			cin>>x1>>op>>x2;
  39. 			if(op=="="){
  40. 				adj[x1].push_back(x2);
  41. 				adj[x2].push_back(x1);
  42. 			}
  43. 			else
  44. 				queries.push_back({x1,x2});
  45. 		}
  46.  
  47. 		for(int i = 1;i<=n;i++){
  48. 			if(vis[i]==0){
  49. 				cc_cnt++;
  50. 				dfs(i);
  51. 			}
  52. 		}
  53. 		for(int i =0;i<queries.size();i++){
  54. 			int a = queries[i].first;
  55. 			int b = queries[i].second;
  56.  
  57. 			if(cc[a]==cc[b]){
  58. 				flag = false;
  59. 				break;
  60. 				}
  61. 		}
  62.  
  63. 		if(flag)
  64. 			cout<<"YES"<<endl;
  65. 		else
  66. 			cout<<"NO"<<endl;
  67.  
  68.  
  69. 	}
  70.  
  71. }
Runtime error #stdin #stdout 0.01s 27008KB
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https://ideone.com/M9BWo4
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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