Question

It is C++ problems, please explain your each line of code as well.

Task 1: Implement/ Hard Code a Doubly Linked Lists and make it a Stack. Do not use ::list:: class from the STD library for this example. The user will input a string and the program will output the string backwards. Displaying correct Stack implementation. Utilize the conventional static methods as needed. push() pop() empty() peek() peek() Sample Execution Please input String: happy yppah Task 2: Implement / Hard Code a Doubly Linked Lists and make it a Queue. Do not use ::list:: class from the STD library for this example. The user will input a string and the program will return the string with each letter in the string duplicated Displaying correct Queue implementation. Methods as needed. enqueue() / push_back() . dequeue() / pop_front() Sample Execution Please input String: happy hhaappppyy

Answer 1

task-1:

#include <iostream>
#include <fstream>
#include <string>

using std::cout;

class Node
{
public:
    Node *prev;
    Node *next;
    int shares;
    float pps;
    Node(int vshares, float vpps)
    {
        shares = vshares;
        pps = vpps;
        prev = next = nullptr;
    }
};

class dlist
{
public:
    Node *head;
    Node *tail;

    dlist()
    {
        head = tail = nullptr;
    }
    ~dlist()
    {
        destroy();
    }

    void push_back(int shares, float pps) 
    {
        Node *node = new Node(shares, pps);
        if (head == NULL) 
        {
            head = tail = node;
        }
        else 
        {
            tail->next = node;
            node->prev = tail;
            tail = node;
        }
    }

    void destroy() 
    {
        Node *walk = head;
        while (walk) 
        {
            Node *node = walk;
            walk = walk->next;
            delete node;
        }
        head = tail = nullptr;
    }
};

class stack
{
public:
    int maxsize;
    int count;
    dlist list;
    stack(int size)
    {
        count = 0;
        maxsize = size;
    }

    void push(int num, float price)
    {
        if (count < maxsize)
        {
            list.push_back(num, price);
            count++;
        }
    }

    void pop()
    {
        Node *tail = list.tail;
        if (!tail)
        {
            //already empty
            return;
        }

        if (tail == list.head)
        {
            //only one element in the list
            delete tail;
            list.head = list.tail = nullptr;
            count--;
        }
        else
        {
            Node *temp = list.tail->prev;
            delete list.tail;
            list.tail = temp;
            list.tail->next = nullptr;
            count--;
        }
    }

    void display()
    {
        Node  *walk = list.tail;
        while (walk)
        {
            cout << "("<< walk->pps << ") ";
            walk = walk->prev;
        }
        cout << "\n";
    }
};

int main()
{
    stack s(10);
     string str;
     cout<<"enter the string";
    getline(cin,str);
    for(int i=0;i<s.length();i++)
   {
    s.push(i,str[i]);
   }
    s.display();
}

task-2:

1. #include <iostream>
2. using namespace std;
3. struct Node {
4. int data;
5. Node* next;
6. };
7. class Queue {
8. struct Node* head,* tail;
9. public:
10. Queue() {
11. head = tail = NULL;
12. }
13. void enQueue();
14. void deQueue();
15. void displayQueue();
16. void menu();
17. int elem;
18. int choice;
19. };
20. void Queue::enQueue(char c) {
21. Node* pointer = new Node;
22. pointer -> data = c;
23. pointer -> next = NULL;
24. if(head == NULL) {
25. head = pointer;
26. }
27. else
28. tail -> next = pointer;
29. tail = pointer;
30. }
31. void Queue::deQueue() {
32. if(head == NULL){
33. cout << "Queue is empty!" << endl;
34. }
35. Node* temp = head;
36. head = head -> next;
37. delete temp;
38. }
39. void Queue::displayQueue() {
40. Node* pointer1 = head;
41. while (pointer1 != NULL) {
42. cout << pointer1 -> data;
43. cout << pointer1 -> data ;
44. pointer1 = pointer1 -> next;
45. }
46. cout << "End" << endl;
47. }
48. int main () {
49. Queue q1;
50. string str;
    cout<<"enter the string"; getline(cin,str);
    for(int i=0;i<s.length();i++)
    {
    q1.enque(s[i]);
    }
51. q1.display();
52. }