Question

C++ Given Stack Code, Implements Queue. enqueue, dequeue. Modify to function like Queue.


Stack
#ifndef STACK_H
#define STACK_H

#include "Node.h"


 
 template
 class Stack {
 private:
    
     Node* top;

 public:
     // Constructor
     Stack() {
      
         top = nullptr;
     }

    
    

    
     void push(Object ab) {
         
         if (top != nullptr) {
            
             Node* newNode = new Node(ab, *top);
   
             top = newNode;
         } else {
             
             Node* newNode = new Node(ab);
            
             top = newNode;
         }
     }

     
     Object pop() {
        
         if (top != nullptr) {
             Node *returnVal = top;
            
             top = top->getNext();
             Object returnObject = returnVal->getItem();
             
             delete returnVal; 
             return returnObject;
         } else {
            
             return Object();
         }
     }

    
     bool isThere(Object a) {
         Node* Copy = top;
        
         while (Copy != nullptr) {
             if (Copy->getItem() == a) {
                 
                 return true;
             }
             
             Copy = Copy->getNext();
         }
        
         return false;
     }


    
 };


#endif //STACK_H

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Answer 1

Queue
#ifndef STACK_H
#define STACK_H

#include "Node.h"


 
 template
 class Stack {
 private:
    
     Node* top;

 public:
     // Constructor
     Stack() {
      
         top = nullptr;
     }

    
    

    // enqueue() operation will be same as push(), changes sholud be made only in pop() method to implement //dequeue()
     void push(Object ab) {
         
         if (top != nullptr) {
            
             Node* newNode = new Node(ab, *top);
   
             top = newNode;
         } else {
             
             Node* newNode = new Node(ab);
            
             top = newNode;
         }
     }

     
     Object pop() {
        Node * previous; // to previous node address
         Node * front; // to hold the address of front node
         front=top; //initialize front with top address
         if (front== nullptr) {    // zero node case
               return Object();
         }

          if(front.getNext() == nullptr) // single node case
           {
            top=nullptr;
             Object returnObject = front.getItem();
              delete front;
               return returnObject;  
            }

          while(front.getNext()!=nullptr)// more than one node case
           {
               previous=front;
                front=front.getNext();
            }
                 
             previous.Next=nullptr; /*include this line only if know what attribute is defined inside the Node struct/class to hold the link of next node in current node to set the second 
bottom-most node's next field to point nullptr. so replace the attribute "Next" by actual attribute that is defined in Node struct/class.*/
               Object returnObject = front.getItem();
              delete front;
               return returnObject;
     }

    
     bool isThere(Object a) {
         Node* Copy = top;
        
         while (Copy != nullptr) {
             if (Copy->getItem() == a) {
                 
                 return true;
             }
             
             Copy = Copy->getNext();
         }
        
         return false;
     }


    
 };


#endif //STACK_H