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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	int t;
  6. 	cin>>t;
  7. 	while(t--){
  8. 		int w;
  9. 		cin>>w;
  10. 		bool res = true;
  11. 		if(w%2 == 0){
  12. 			res = false;
  13. 		}
  14. 		int i = 1;
  15. 		int c = w;
  16.  
  17. 		while(c--){
  18. 			int h;
  19. 			cin>>h;
  20. 			if(c*2>w){
  21. 				if(h!=i++) {
  22. 					res = false;
  23. 				}}
  24. 			else{
  25. 				if(h!=i--) {
  26. 					res = false;
  27. 				}}
  28. 		}
  29. 		if(res) cout<<"yes\n";
  30. 		else cout<<"no\n";
  31. 	}
  32. 	return 0;
  33. }
Success #stdin #stdout 0s 16048KB
comments (?)
stdin
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7
5
1 2 3 2 1
7
2 3 4 5 4 3 2
5
1 2 3 4 3
5
1 3 5 3 1
7
1 2 3 4 3 2 1
4
1 2 3 2
4
1 2 2 1
stdout
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yes
no
no
no
yes
no
no
https://ideone.com/LMwlU3
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
public

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