Question

In C++

In this lab we will be creating a stack class and a queue class, both with a hybrid method combining linked list and arrays in addition to the Stack methods(push, pop, peek, isEmpty, size, print) and Queue methods (enqueue, deque, peek, isEmpty, size, print).

DO NOT USE ANY LIBRARY, implement each method from scratch.

Both the Stack and Queue classes should be generic classes.

Don't forget to comment your code.

Answer 1

Stack using Link List

// C++ program to Implement a stack 
//using singly linked list 
#include <bits/stdc++.h> 
using namespace std; 

// Declare linked list node 

struct Node 
{ 
        int data; 
        struct Node* link; 
}; 

struct Node* top; 

// Utility function to add an element 
// data in the stack insert at the beginning 
void push(int data) 
{ 
        
        // Create new node temp and allocate memory 
        struct Node* temp; 
        temp = new Node(); 

        // Check if stack (heap) is full. 
        // Then inserting an element would 
        // lead to stack overflow 
        if (!temp) 
        { 
                cout << "\nHeap Overflow"; 
                exit(1); 
        } 

        // Initialize data into temp data field 
        temp->data = data; 

        // Put top pointer reference into temp link 
        temp->link = top; 

        // Make temp as top of Stack 
        top = temp; 
} 

// Utility function to check if 
// the stack is empty or not 
int isEmpty() 
{ 
        return top == NULL; 
} 

// Utility function to return top element in a stack 
int peek() 
{ 
        
        // Check for empty stack 
        if (!isEmpty()) 
                return top->data; 
        else
                exit(1); 
} 

// Utility function to pop top 
// element from the stack 
void pop() 
{ 
        struct Node* temp; 

        // Check for stack underflow 
        if (top == NULL) 
        { 
                cout << "\nStack Underflow" << endl; 
                exit(1); 
        } 
        else
        { 
                
                // Top assign into temp 
                temp = top; 

                // Assign second node to top 
                top = top->link; 

                // Destroy connection between 
                // first and second 
                temp->link = NULL; 

                // Release memory of top node 
                free(temp); 
        } 
} 

// Function to print all the 
// elements of the stack 
void display() 
{ 
        struct Node* temp; 

        // Check for stack underflow 
        if (top == NULL) 
        { 
                cout << "\nStack Underflow"; 
                exit(1); 
        } 
        else
        { 
                temp = top; 
                while (temp != NULL) 
                { 

                        // Print node data 
                        cout << temp->data << "-> "; 

                        // Assign temp link to temp 
                        temp = temp->link; 
                } 
        } 
} 

// Driver Code 
int main() 
{ 
        
        // Push the elements of stack 
        push(11); 
        push(22); 
        push(33); 
        push(44); 

        // Display stack elements 
        display(); 

        // Print top element of stack 
        cout << "\nTop element is "
                << peek() << endl; 

        // Delete top elements of stack 
        pop(); 
        pop(); 

        // Display stack elements 
        display(); 

        // Print top element of stack 
        cout << "\nTop element is "
                << peek() << endl; 
                
        return 0; 
} 

Stack using array

/* C++ program to implement basic stack 
operations */
#include <bits/stdc++.h> 

using namespace std; 

#define MAX 1000 

class Stack { 
        int top; 

public: 
        int a[MAX]; // Maximum size of Stack 

        Stack() { top = -1; } 
        bool push(int x); 
        int pop(); 
        int peek(); 
        bool isEmpty(); 
}; 

bool Stack::push(int x) 
{ 
        if (top >= (MAX - 1)) { 
                cout << "Stack Overflow"; 
                return false; 
        } 
        else { 
                a[++top] = x; 
                cout << x << " pushed into stack\n"; 
                return true; 
        } 
} 

int Stack::pop() 
{ 
        if (top < 0) { 
                cout << "Stack Underflow"; 
                return 0; 
        } 
        else { 
                int x = a[top--]; 
                return x; 
        } 
} 
int Stack::peek() 
{ 
        if (top < 0) { 
                cout << "Stack is Empty"; 
                return 0; 
        } 
        else { 
                int x = a[top]; 
                return x; 
        } 
} 

bool Stack::isEmpty() 
{ 
        return (top < 0); 
} 

// Driver program to test above functions 
int main() 
{ 
        class Stack s; 
        s.push(10); 
        s.push(20); 
        s.push(30); 
        cout << s.pop() << " Popped from stack\n"; 

        return 0; 
} 

Queue using link list

#include <bits/stdc++.h> 
using namespace std; 

struct QNode { 
        int data; 
        QNode* next; 
        QNode(int d) 
        { 
                data = d; 
                next = NULL; 
        } 
}; 

struct Queue { 
        QNode *front, *rear; 
        Queue() 
        { 
                front = rear = NULL; 
        } 

        void enQueue(int x) 
        { 

                // Create a new LL node 
                QNode* temp = new QNode(x); 

                // If queue is empty, then 
                // new node is front and rear both 
                if (rear == NULL) { 
                        front = rear = temp; 
                        return; 
                } 

                // Add the new node at 
                // the end of queue and change rear 
                rear->next = temp; 
                rear = temp; 
        } 

        // Function to remove 
        // a key from given queue q 
        void deQueue() 
        { 
                // If queue is empty, return NULL. 
                if (front == NULL) 
                        return; 

                // Store previous front and 
                // move front one node ahead 
                QNode* temp = front; 
                front = front->next; 

                // If front becomes NULL, then 
                // change rear also as NULL 
                if (front == NULL) 
                        rear = NULL; 

                delete (temp); 
        } 
}; 

// Driven Program 
int main() 
{ 

        Queue q; 
        q.enQueue(10); 
        q.enQueue(20); 
        q.deQueue(); 
        q.deQueue(); 
        q.enQueue(30); 
        q.enQueue(40); 
        q.enQueue(50); 
        q.deQueue(); 
        cout << "Queue Front : " << (q.front)->data << endl; 
        cout << "Queue Rear : " << (q.rear)->data; 
} 

Queue using Array

// C++ program to implement a queue using an array 
#include <bits/stdc++.h> 
using namespace std; 

struct Queue { 
        int front, rear, capacity; 
        int* queue; 
        Queue(int c) 
        { 
                front = rear = 0; 
                capacity = c; 
                queue = new int; 
        } 

        ~Queue() { delete[] queue; } 

        // function to insert an element 
        // at the rear of the queue 
        void queueEnqueue(int data) 
        { 
                // check queue is full or not 
                if (capacity == rear) { 
                        printf("\nQueue is full\n"); 
                        return; 
                } 

                // insert element at the rear 
                else { 
                        queue[rear] = data; 
                        rear++; 
                } 
                return; 
        } 

        // function to delete an element 
        // from the front of the queue 
        void queueDequeue() 
        { 
                // if queue is empty 
                if (front == rear) { 
                        printf("\nQueue is empty\n"); 
                        return; 
                } 

                // shift all the elements from index 2 till rear 
                // to the left by one 
                else { 
                        for (int i = 0; i < rear - 1; i++) { 
                                queue[i] = queue[i + 1]; 
                        } 

                        // decrement rear 
                        rear--; 
                } 
                return; 
        } 

        // print queue elements 
        void queueDisplay() 
        { 
                int i; 
                if (front == rear) { 
                        printf("\nQueue is Empty\n"); 
                        return; 
                } 

                // traverse front to rear and print elements 
                for (i = front; i < rear; i++) { 
                        printf(" %d <-- ", queue[i]); 
                } 
                return; 
        } 

        // print front of queue 
        void queueFront() 
        { 
                if (front == rear) { 
                        printf("\nQueue is Empty\n"); 
                        return; 
                } 
                printf("\nFront Element is: %d", queue[front]); 
                return; 
        } 
}; 

// Driver code 
int main(void) 
{ 
        // Create a queue of capacity 4 
        Queue q(4); 

        // print Queue elements 
        q.queueDisplay(); 

        // inserting elements in the queue 
        q.queueEnqueue(20); 
        q.queueEnqueue(30); 
        q.queueEnqueue(40); 
        q.queueEnqueue(50); 

        // print Queue elements 
        q.queueDisplay(); 

        // insert element in the queue 
        q.queueEnqueue(60); 

        // print Queue elements 
        q.queueDisplay(); 

        q.queueDequeue(); 
        q.queueDequeue(); 

        printf("\n\nafter two node deletion\n\n"); 

        // print Queue elements 
        q.queueDisplay(); 

        // print front of the queue 
        q.queueFront(); 

        return 0; 
}