import java.util.Iterator;
public class ListTable<K, V> implements Table<K, V>, Iterable<K>
{
    private Node<K, V> head = null;
    public int nodecount = 0;
    public long getitcount = 0;
    
    public void put(K key, V value) {
        Node<K,V> n = new Node<K,V>(key, value, head);
        head=n;
        nodecount++;
    }
    public V get(K key) {
        for (Node<K,V> n = head; n != null; n = n.next) {
            getitcount++;
            if (key.equals(n.key))
                return n.value;
        }
        return null;
    }
    public void remove(K key) {
        if (head!=null) {
            if (key.equals(head.key)) {
                head = head.next;
            }
            for (Node<K,V> n = head; n!=null && n.next != null; n = n.next) {
                if (key.equals(n.next.key)) {
                    n.next = n.next.next;
                }
            }
        }
    }

    public Iterator<K> iterator() {
        return new LTI<K>(head);
    }

    private class Node<K, V> {
        private K key;
        private V value;
        private Node<K,V> next;

        Node(K k, V v, Node<K,V> l) {
            key = k;
            value = v;
            next = l;
        }
    }

    private class LTI<K> implements Iterator<K> {
        private Node<K,V> c;
        LTI(Node<K,V> head) {
            c=head;
        }
        public boolean hasNext() {
            return c!=null;
        }
        public K next() {
            K k=c.key;
            c = c.next;
            return k;
        }
        public void remove() {
            throw new UnsupportedOperationException();
        }
    }
}