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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main(){
  5. 	string a;	cin >> a;
  6. 	a = '0'+a+'0';
  7. 	for(int i=1;i<a.size()-1;++i){
  8. 		if(a[1] == '4' || (a[i] != '1' && a[i] != '4')){
  9. 			cout << "NO";
  10. 			return 0;
  11. 		}else if(a[i] == '1')	continue;
  12. 		else{
  13. 			if(a[i-1] == '1' || a[i+1] == '1')	continue;
  14. 			else if(a[i-1] == '4' && a[i+1] != '4')	continue;
  15. 			else if(a[i-1] != '4' && a[i+1] == '4')	continue;
  16. 			else{
  17. 				cout << "NO";
  18. 				return 0;
  19. 			}
  20. 		}
  21. 	}
  22. 	cout << "YES";
  23. 	return 0;
  24. }
Success #stdin #stdout 0.01s 5272KB
comments (?)
stdin
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1114141441
stdout
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YES
https://ideone.com/MK4POV
language:
C++14 (clang 8.0)
created:
5 days ago
visibility:
public

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