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  1. #include <iostream>
  2. #include <stack>
  3. #include <string>
  4.  
  5. using namespace std;
  6.  
  7. bool hasHigherPreference(char s_top, char c){
  8.  
  9.   if ((c == '*' || c== '/') && (s_top == '+' || s_top == '-'))
  10.     return true;
  11.  
  12.   return false;
  13. }
  14.  
  15. bool isOperator(char c){
  16.  
  17.   if (c == '+' || c == '-' || c == '*' || c== '/')
  18.     return true;
  19.  
  20.  
  21.   return false;
  22.  
  23. }
  24. int main() {
  25.   int t;
  26.   char c;
  27.   stack<char> s;
  28.   string postfix = "";
  29.  
  30.   cin >> t;
  31.   cin.ignore(1000, '\n');
  32.  
  33.     while (t--) {
  34.       cin.ignore(1000, '\n');
  35.  
  36.       while (cin.peek() != '\n' && cin.peek() != -1) {
  37.         cin >> c;
  38.         cin.ignore(100, '\n');
  39.  
  40.         if (c == '(')
  41.           s.push(c);
  42.         else if(c==')'){
  43.           while(s.top() != '('){
  44.             postfix += s.top();       
  45.             s.pop();          
  46.           }
  47.           s.pop();
  48.         } else if (!isOperator(c)) {
  49.           postfix += c;
  50.         } else if (s.empty() || hasHigherPreference(s.top(),c)){
  51.           s.push(c);
  52.         } else {
  53.           postfix += s.top();
  54.           s.pop();
  55.           s.push(c);
  56.         }
  57.       }
  58.  
  59.       while(!s.empty()){
  60.         postfix += s.top();
  61.         s.pop();
  62.       }
  63.  
  64.  
  65.  
  66.       cout << postfix << endl;
  67.     }
  68. }
Success #stdin #stdout 0.02s 4472KB
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https://ideone.com/K9aFXB
language:
C++ (gcc 8.3)
created:
4 years ago
visibility:
public

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