public class IntegerLinkedList implements IntegerList {
    
	private Node head;
	private int numElements;

	public IntegerLinkedList() {
		head = null;
		numElements = 0;
	}

	public void addFront (int val) {
		Node n = new Node(val);
		n.next = head;		
		head = n;
		numElements++;
	}

	public void addBack (int val) {
		Node n = new Node(val);
		
		if (head == null) { // nothing in the list
			head = n;
		} else {
			// traverse the list until we get to the end, 
			// so we can add n to the back of the list
			Node cur = head;
			while (cur.next != null) {
				cur = cur.next;
			}
			// cur is the last node in the list
			cur.next = n;
		}
		
		numElements++;
	}

	public int size (){
		return numElements;
	}

	public int get (int position) {
		Node cur = head;
		for (int i = 0; i < position; i++) {
			cur = cur.next;
		}
		return cur.getValue();
	}

	/* Purpose: create a string representation of list 
	 * Parameters: none
	 * Returns: String - the string representation
	 */
	public String toString() {
		String s = "List contents:";
		
		Node cur = head;
		while (cur != null) {
			s += " " + cur.getValue();
			cur = cur.next;
		}

		return s;
	}    
}