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  1. #include<iostream>
  2. #include<string.h>
  3. using namespace std;
  4. class stk{
  5.     private: char c[20];
  6.     private: int id=-1;
  7.     public: int isempty(){
  8.         if(id==-1)
  9.              return 1;
  10.          else
  11.               return 0;
  12.     }
  13.     public: void push(char o){
  14.         c[++id]=o;
  15.     }
  16.     public: char pop(){
  17.         return c[id--];
  18.     }
  19. };
  20.  
  21. int main(){
  22.     stk stack;
  23.     char n[21];
  24.     char preo;
  25.     int i=0;
  26.     cin>>n;
  27.     int f=1;
  28.     while(i<strlen(n)){
  29.         if(n[i]>='0'&&n[i]<='9'){
  30.             if(f)
  31.                f=0;
  32.              else
  33.                cout<<" ";
  34.              while(i<strlen(n)&&n[i]>='0'&&n[i]<='9'){
  35.                  cout<<n[i];
  36.                  i++;
  37.              }
  38.         }
  39.         if(i<strlen(n)){
  40.         if(stack.isempty())
  41.             stack.push(n[i++]);
  42.         else{
  43.             preo=stack.pop();
  44.             if(n[i]=='+'||n[i]=='-'){
  45.                  if(preo!='(')
  46.                 cout<<" "<<preo;
  47.                 else
  48.                 stack.push(preo);
  49.                 stack.push(n[i]);
  50.             }else if(n[i]=='*'||n[i]=='/'){
  51.                 if(preo=='*'||preo=='/')
  52.                     cout<<" "<<preo;
  53.                 else
  54.                     stack.push(preo);
  55.                 stack.push(n[i]);
  56.  
  57.             }else if(n[i]=='('){
  58.                 stack.push(preo);
  59.                 stack.push(n[i]);
  60.             }else{
  61.                 while(preo!='('){
  62.                     cout<<" "<<preo;
  63.                     preo=stack.pop();
  64.                 }
  65.             }
  66.             i++;
  67.         }
  68.         }
  69.     }
  70.     while(!stack.isempty())
  71.        cout<<" "<<stack.pop();
  72. }
Success #stdin #stdout 0s 3472KB
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2 3 7 4 - * +
https://ideone.com/ZwjEJs
language:
C++14 (clang 8.0)
created:
7 years ago
visibility:
public

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