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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. string s , temp;
  4. stack < char > stk;
  5. char ch;
  6. int n , m , sz;
  7. int operator_value( char op );
  8. string Infix_To_Postfix();
  9. int main()
  10. {
  11.     cin>>s;
  12.     reverse( s.begin(), s.end() );
  13.     s = Infix_To_Postfix();
  14.     cout<<s<<endl;
  15.     return 0;
  16. }
  17. string Infix_To_Postfix()
  18. {
  19.     sz = s.size();
  20.     for ( int i = 0; i != sz; i++ )
  21.     {
  22.         if ( s [ i ] >= 'a' && s [ i ] <= 'z' )temp += s [ i ];
  23.         else if ( s [ i ] == ')' )stk.push( s [ i ] );
  24.         else if ( s [ i ] == '(' )
  25.         {
  26.             while ( !stk.empty() && stk.top() != ')' )
  27.             {
  28.                 ch = stk.top();
  29.                 stk.pop();
  30.                 temp += ch;
  31.             }
  32.             stk.pop();
  33.         }
  34.         else
  35.         {
  36.             while ( !stk.empty() && operator_value( s [ i ] ) <= operator_value( stk.top() ) )
  37.             {
  38.                 ch = stk.top();
  39.                 stk.pop();
  40.                 if ( ch != ')' && ch != '(' )temp += ch;
  41.             }
  42.             stk.push( s [ i ] );
  43.         }
  44.     }
  45.     while ( !stk.empty() )
  46.     {
  47.         if ( stk.top() != '(' && stk.top() != ')' )temp += stk.top();
  48.         stk.pop();
  49.     }
  50.     reverse ( temp.begin() , temp.end() );
  51.     return temp;
  52. }
  53. int operator_value( char op )
  54. {
  55.     if ( op == '^' )return 3;
  56.     if ( op == '*' || op == '/' )return 2;
  57.     if ( op == '+' || op == '-' )return 1;
  58.     return -1;
  59. }
  60.  
Success #stdin #stdout 0s 4508KB
comments (?)
stdin
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(a+b)*(b-c)
stdout
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*+ab-bc
https://ideone.com/Afvgkz
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
secret

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