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Week 3  ----------------------------------------

import java.util.Stack;

class StackOfIntegers {
    private Stack<Integer> stack;

    public StackOfIntegers() {
        stack = new Stack<>();
    }

    public void push(int value) {
        stack.push(value);
    }

    public int pop() {
        return stack.pop();
    }

    public void displayFromTop() {
        System.out.println("Stack contents from top to bottom: " + stack);
    }

    public void displayFromBot() {
        Stack<Integer> temp = new Stack<>();
        while (!stack.isEmpty()) {
            temp.push(stack.pop());
        }
        System.out.println("Stack contents from bottom to top: " + temp);
        while (!temp.isEmpty()) {
            stack.push(temp.pop());
        }
    }

    public int stackTop() {
        return stack.peek();
    }

    public boolean isEmpty() {
        return stack.isEmpty();
    }

    public boolean isFull() {
        // Stack does not have a fixed size, so it is not possible to determine if it is full
        return false;
    }
}





Week 3 q2 -------------------------------------------------------

public class IntegerLinkedList {
    private Node head;

    private static class Node {
        int data;
        Node next;

        public Node(int data) {
            this.data = data;
            this.next = null;
        }
    }

    public boolean isEmpty() {
        return head == null;
    }

    public void display() {
        if (isEmpty()) {
            System.out.println("List is empty.");
            return;
        }
        Node current = head;
        while (current != null) {
            System.out.print(current.data + " -> ");
            current = current.next;
        }
        System.out.println("null");
    }

    public void addAtLast(int value) {
        Node newNode = new Node(value);
        if (isEmpty()) {
            head = newNode;
            return;
        }
        Node current = head;
        while (current.next != null) {
            current = current.next;
        }
        current.next = newNode;
    }

    public void deleteAtHead() {
        if (isEmpty()) {
            throw new RuntimeException("List is empty. Cannot delete head.");
        }
        head = head.next;
    }

    public static void main(String[] args) {
        IntegerLinkedList list = new IntegerLinkedList();

        list.addAtLast(10);
        list.addAtLast(20);
        list.addAtLast(30);

        System.out.println("List after adding 10, 20, 30:");
        list.display();

        System.out.println("Deleting head of the list:");
        list.deleteAtHead();
        list.display();

        System.out.println("Deleting head of the list:");
        list.deleteAtHead();
        list.display();
    }
}