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  1. #include<bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define ll long long 
  6.  
  7. // map<int,vector<int>>adj;
  8. vector<int>adj[1000001];
  9. int cc_cnt = 0;
  10. // map<int,bool>vis;
  11. int vis[1000001];
  12. // vector<int>cc(1000001,0);
  13. int cc[1000001];
  14. // int find(int a,int par[]){
  15. // 	if(par[a]<0)
  16. // 		return a;
  17. // 	return par[a] = find(par[a],par);
  18. // }
  19. // void unionset(int a,int b,int par[]){
  20. // 	int para = find(a,par);
  21. // 	int parb = find(b,par);
  22. // 	if(para!=parb){
  23. // 		par[para]+=par[parb];
  24. // 		par[parb] = para;
  25. // 	}
  26. // }
  27.  
  28. void dfs(int x){
  29. 	vis[x] = 1;
  30. 	cc[x] = cc_cnt;
  31. 	for(int neigh:adj[x])
  32. 		if(vis[neigh]==0)
  33. 			dfs(neigh);
  34.  
  35. }
  36.  
  37. int main(){
  38. 	int t;
  39. 	cin>>t;
  40. 	while(t--){
  41. 		// adj.clear();
  42. 		int n,k;
  43. 		cin>>n>>k;
  44. 		int flag = 1;
  45. 		vector<pair<int,int>>queries;			
  46. 		for(int i=0;i<=n;i++){
  47. 			vis[i] = 0;
  48. 			adj[i].clear();
  49. 			}
  50. 		for(int i =0;i<=n;i++)
  51. 			cc[i] = 0;
  52. 		cc_cnt =0;
  53. 		while(k--){
  54. 			int x1,x2;
  55. 			string op;
  56. 			cin>>x1>>op>>x2;
  57. 			if(op=="="){
  58. 				adj[x1].push_back(x2);
  59. 				adj[x2].push_back(x1);
  60. 			}
  61. 			else
  62. 				queries.push_back({x1,x2});
  63. 		}
  64.  
  65. 		for(int i = 1;i<=n;i++){
  66. 			if(vis[i]==0){
  67. 				cc_cnt++;
  68. 				dfs(i);
  69. 			}
  70. 		}
  71. 		for(int i =0;i<queries.size();i++){
  72. 			int a = queries[i].first;
  73. 			int b = queries[i].second;
  74.  
  75. 			if(cc[a]==cc[b]){
  76. 				flag = 0;
  77. 				break;
  78. 				}
  79. 		}
  80.  
  81. 		if(flag)
  82. 			cout<<"YES"<<endl;
  83. 		else
  84. 			cout<<"NO"<<endl;
  85.  
  86.  
  87. 	}
  88.  
  89. }
Runtime error #stdin #stdout 0.01s 30620KB
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https://ideone.com/VTwoc2
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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