public class MyLinkedList implements MyList {
	
	private MyLListNode head = null;
	
	class MyLListNode {
		private int key;
		private MyLListNode next;
		
		MyLListNode (int val) {
			key = val;
			next = null;
		}
	}
	
	MyLinkedList() {
		head = null;
	}
	
	public void makeEmpty() {
		head = null;
	}
	
	public boolean isEmpty() {
		return (head==null);
	}
	
	public void printList() {
		if (head == null) 
			System.err.println("Empty list");
		else {
			MyLListNode curr = head;
			System.err.print("LList elements: ");
			while (curr != null) {
				System.err.print(curr.key + " ");
				curr = curr.next;
			}
			System.err.println();
		}
	}

	public int size() {
		if (head == null) 
			return 0;
		else {
			int size = 0;
			MyLListNode curr = head;
			while (curr != null) {
				size++;
				curr = curr.next;
			}
			return size;
		}
	}
		
	public boolean contains(int key) {
		if (isEmpty())
			return false;
		else {
			boolean result = false;
			MyLListNode curr = head;
			while ((curr != null) && !result) {
				if (curr.key == key)
					result = true;
				curr = curr.next;
			}
			return result;
		}
	}
	
	public int get(int index) {
		// should handle out of bounds case with an exception but won't ...
		if ((index < 0) || (index >= size()))
			return -1; // silly - but we'll assume only positive keys
		else {
			int i = 0;
			MyLListNode curr = head;
			while (i < index) {
				curr = curr.next;
				i++;
			}
			return curr.key;
		}
	}
	
	public void set(int index, int key) {
		// should handle out of bounds case with an exception but won't ...
		if ((index < 0) || (index >= size())) {
			System.err.println("Error: attempt to set non-existent list item");
			return; // silly - but we'll assume only positive keys
		} else {
			int i = 0;
			MyLListNode curr = head;
			while (i < index) {
				curr = curr.next;
				i++;
			}
			curr.key = key;
		}
	}
	
	public void add(int index, int key) {
		// should handle out of bounds case with an exception but won't ...
		if ((index < 0) || (index > size())) {
			System.err.println("Error: attempt to add item out of range");
		} else if (index == 0) {
			MyLListNode newNode = new MyLListNode(key);
			newNode.next = head;
			head = newNode;
		} else {
			MyLListNode newNode = new MyLListNode(key);
			MyLListNode prev = head;
			int i = 1;
			while (i < index) {
				prev = prev.next;
				i++;
				}
			newNode.next = prev.next;
			prev.next = newNode;
			}
		}

	public void remove(int index) {
		// should handle out of bounds case with an exception but won't ...
		if ((index < 0) || (index >= size())) {
			System.err.println("Error: attempt to remove item out of range");
		} else if (index == 0) {
			head = head.next;
		} else {
			MyLListNode prev = head;
			int i = 1;
			while (i < index) {
				prev = prev.next;
				i++;
				}
			prev.next = prev.next.next;
			}
	}
	
	public static void main(String[] args) { 
		MyList l = new MyLinkedList();
		l.printList();
		System.err.println(l.isEmpty());
		System.err.println(l.size());
		l.add(0, 3);
		l.printList();
		l.add(0,4);
		l.add(0,2);
		l.printList();
		System.err.println(l.get(1));
		//l.remove(4);
		l.remove(1);
		l.printList();
		l.add(1,5);
		l.add(1,6);
		l.add(l.size(), 7);
		l.printList();
		l.remove(2);
		l.printList();
	}
}