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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	int t;
  6. 	cin >> t;
  7. 	while(t--){
  8. 		int n,k;
  9. 		cin >> n >> k;
  10. 		int a[n];
  11. 		int x;
  12. 		int c[n+1];
  13. 		for(int i=0;i<n;i++){
  14. 			cin >> a[i];
  15. 			c[i+1] = a[i];
  16. 			if(i == 0){
  17. 				x = a[i];
  18. 			}
  19. 			else{
  20. 				x = x ^ a[i];
  21. 			}
  22. 		}
  23. 		vector<set<int>> b(n+1);
  24. 		for(int i=0;i<n-1;i++){
  25. 			int y,z;
  26. 			cin >> y >> z;
  27. 			b[y].insert(z);
  28. 			b[z].insert(y);
  29. 		}
  30. 		if(x == 0){
  31. 			cout << "YES" << endl;
  32. 		}
  33. 		else{
  34. 			if(k == 2){
  35. 				cout << "NO" << endl;
  36. 			}
  37. 			else{
  38. 				stack<int> st;
  39. 				st.push(1);
  40. 				int cnt(0);
  41. 				while(st.size() > 0){
  42. 					int tp = st.top();
  43. 					if(b[tp].size() > 0){
  44. 						int fir = *b[tp].begin();
  45. 						b[fir].erase(tp);
  46. 						b[tp].erase(fir);
  47. 						st.push(fir);
  48. 					}
  49. 					else{
  50. 						int s = st.top();
  51. 						if(c[s] == x){
  52. 							cnt++;
  53. 						}
  54. 						st.pop();
  55. 						if(st.size() > 0){
  56. 							int zz = st.top();
  57. 							// cout << zz << " " << s << endl;
  58.  
  59. 							if(c[s] != x){
  60. 								c[zz] = c[zz] ^ c[s];
  61. 							}
  62.  
  63.  
  64. 						}
  65. 					}
  66. 				}
  67.  
  68. 				if(cnt >= 2){
  69. 					cout << "YES" << endl;
  70. 				}
  71. 				else{
  72. 					cout << "NO" << endl;
  73. 				}
  74.  
  75. 			}
  76. 		}
  77.  
  78. 	}
  79. 	return 0;
  80. }
Success #stdin #stdout 0.01s 5500KB
comments (?)
stdin
copy 
5
2 2
1 3
1 2
5 5
3 3 3 3 3
1 2
2 3
1 4
4 5
5 2
1 7 2 3 5
1 2
2 3
1 4
4 5
5 3
1 6 4 1 2
1 2
2 3
1 4
4 5
3 3
1 7 4
1 2
2 3
stdout
copy 
NO
YES
NO
YES
NO
https://ideone.com/H4JFWw
language:
C++14 (gcc 8.3)
created:
326 days ago
visibility:
public

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