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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. class Stack{
  5. private:
  6.     int *arr { nullptr };
  7.     int size {};
  8.     int top {};
  9. public:
  10.     Stack(){
  11.         size = 20;
  12.         arr = new int[size]{ };
  13.         top = -1;
  14.     }
  15.     ~Stack(){
  16.         delete[] arr;
  17.         arr = nullptr;
  18.     }
  19.     void push(char n){
  20.         if(is_full())
  21.             cout << "Stack overflow!!\n";
  22.         assert(-1 <= top && top < size);
  23.         arr[++top] = n;
  24.     }
  25.     int pop(){
  26.         if(is_empty())
  27.             cout << "The Stack is empty!!\n";
  28.         assert(0 <= top && top < size);
  29.         return arr[top--];
  30.     }
  31.     int peek(){
  32.         return arr[top];
  33.     }
  34.     bool is_empty(){
  35.         if (top == -1)
  36.             return true;
  37.         return false;
  38.     }
  39.     bool is_full(){
  40.         if(top == size-1)
  41.             return true;
  42.         return false;
  43.     }
  44.     double PostfixEvaluate(string Ex){
  45.         Stack stk; int N = 0; bool ok = false;
  46.         for(int i=0; i<Ex.size(); i++){
  47.             if (isdigit(Ex[i])){
  48.                 if(!ok) ok = true;
  49.                 N = N*10 + (Ex[i]-'0');
  50.             }
  51.             else {
  52.                 if (ok) stk.push(N), ok = false, N = 0;
  53.                 if(Ex[i]==' ')
  54.                     continue;
  55.                 int y = stk.pop();
  56.                 int x = stk.pop();
  57.                 if (Ex[i]=='+') stk.push(x+y);
  58.                 else if (Ex[i]=='-') stk.push(x-y);
  59.                 else if (Ex[i]=='*') stk.push(x*y);
  60.                 else if (Ex[i]=='/') stk.push(x/y);
  61.             }
  62.         }
  63.         return stk.peek();
  64.     }
  65.     string infix2postfix(string infix){
  66.         Stack stk;
  67.         stk.push('(');
  68.         infix.push_back(')');
  69.         string postfix = "";
  70.         for(int i = 0; i < infix.size(); i++){
  71.             if(isdigit(infix[i]))
  72.                 postfix.push_back(infix[i]);
  73.             else{
  74.                 if(infix[i] == '(')
  75.                     stk.push('(');
  76.                 else if(infix[i] == '*' || infix[i] == '/'){
  77.                     if(stk.peek() == '/' || stk.peek() == '*'){
  78.                         while (stk.peek() != '('){
  79.                             postfix.push_back(stk.pop());
  80.                         }
  81.                     }
  82.                     stk.push(infix[i]);
  83.                 }
  84.                 else if(infix[i] == '+' || infix[i] == '-'){
  85.                     if(stk.peek() != '('){
  86.                         while (stk.peek() != '('){
  87.                             postfix.push_back(stk.pop());
  88.                         }
  89.                     }
  90.                     stk.push(infix[i]);
  91.                 }
  92.                 else if(infix[i] == ')'){
  93.                     while (stk.peek() != '('){
  94.                         postfix.push_back(stk.pop());
  95.                     } stk.pop();
  96.                 }
  97.             }
  98.         }
  99.         return postfix;
  100.     }
  101. };
  102.  
  103. int main() {
  104.     Stack A;
  105.     /*A.push(1);
  106.     A.push(2);
  107.     A.push(3);
  108.     A.push(4);
  109.     A.push(5);
  110.     cout << A.peek() << '\n';
  111.     A.pop();
  112.     A.pop();
  113.     cout << A.peek() << '\n';*/
  114.     //cout << A.PostfixEvaluate("31 82 2 / + 5 -") << '\n'; //67
  115.     //cout << A.PostfixEvaluate("3 8 2/+5 -") << '\n';      //2
  116.     //cout << A.infix2postfix("1+2") << '\n'; //12+
  117.     //cout << A.infix2postfix("(1+2*3-2)") << '\n'; //123*+2-
  118.     //cout << A.infix2postfix("(1+2)*3-2") << '\n'; //12+3*2-
  119.     return 0;
  120. }
  121.  
Success #stdin #stdout 0.01s 5292KB
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https://ideone.com/Ru0BY9
language:
C++ (gcc 8.3)
created:
3 days ago
visibility:
public

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