IntLinkedList.java

public class IntLinkedList {

    public class IntNode {
        public int item;
        private IntNode next;
    
        public IntNode(int i, IntNode n) {
            item = i;
            next = n;
        }
    }

    private int size;
    private IntNode sentinal = new IntNode(-518273, null);

    public IntLinkedList() {
        size = 0;
    }

    public IntLinkedList(int x) {

        sentinal.next = new IntNode(x, null);
        size = 1;
    }

    public void addFirst(int x) {
        IntNode node = new IntNode(x, sentinal.next);
        sentinal.next = node;
        size += 1;
    }

    public int getFirst() {
        return sentinal.next.item;
    }

    public void addLast(int x) {

        IntNode p = sentinal;
        size += 1;

        // if not empty
        while (p.next != null) {
            p = p.next;
        }

        p.next = new IntNode(x, null);
    }

    public int size() {
        return size;
    }
  
    public void clear() {
         // code -- remove all elements from list
    }
    
    public void insert(int idx, int item) {
         // code -- insert item at index idx
    }
    
    public static void main(String[] args) {
        
        IntLinkedList L1 = new IntLinkedList();
        L1.addLast(3);

    }
}