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  1. #include<bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. int prec(char c){
  6. 	switch(c){
  7. 		case'^':
  8. 			return 3;
  9. 		case'/':
  10. 		case'*':
  11. 		    return 2;
  12. 		case'+':
  13. 		case'-':
  14. 		    return 1;
  15. 		default:
  16. 		    return 0;			
  17. 	}
  18. }
  19. void infixtoprefix(char infix[]){
  20. 	stack <char> s;
  21. 	int n = strlen(infix);
  22. 	int i;
  23. 	string out;
  24. 	for(i=0;i<n;i++){
  25. 		if((infix[i] >= 'a' && infix[i] <= 'z')||(infix[i] >= 'A' && infix[i] <= 'Z')){
  26. 			out += infix[i];
  27. 		}
  28. 		else if(infix[i] == '('){
  29. 			s.push('(');
  30. 		}
  31. 		else if(infix[i] == ')'){
  32. 			while(!s.empty() && s.top() != '('){
  33. 				s.pop();
  34. 				out += s.top();
  35. 			}
  36. 		}
  37. 		else{
  38. 			while(!s.empty() && prec(infix[i])<=prec(s.top())){
  39. 				s.pop();
  40. 				out += s.top();
  41. 			}
  42. 			s.push(infix[i]);
  43. 		}
  44. 	}
  45. 	while(s.top() != 'N'){
  46. 		s.pop();
  47. 		out += s.top(); 
  48. 	}
  49. 	cout << out << endl;
  50. }
  51. int main(){
  52. 	char infix[200];
  53. 	int t;
  54. 	cin >> t;
  55. 	while(t--){
  56. 		cin >> infix;
  57. 		infixtoprefix(infix);
  58. 	}
  59. 	return 0;
  60. }
  61.  
Success #stdin #stdout 0s 16072KB
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https://ideone.com/KOy4F0
problem ONP, based on SPOJ submission 19814757 (CPP), 2017-07-17 21:33:38
language:
C++ (gcc 8.3)
created:
6 years ago
visibility:
secret

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