12.8

public int count()
{
   Node current = head;
   int count = 0;
   while (current != null)
   {
      count++;
      current = current.link;
   }
   return count;
}

public void append(int item)
{
   Node temp = new Node(item, null);
   if (head == null)
      head = temp;
   else
   {
      Node current = head;
      while (current.link != null)
         currrent = current.link;
      current.link = temp;
   }
}

public void appendList(List other)
{
   if (head == null)
      head = other.head;
   else
   {
      Node current = head;
      while (current.link != null)
         current = current.link;
      current.link = other.head;
   }
}

public void simplify()
{
   int temp;
   if (head != null)
      temp = head.info;
   else
      return;
   Node current = head.link;
   Node previous = head;
   while (current != null)
   {
      if (temp == current.info)
         previous.link = current.link;
      else
         previous = previous.link;
      current = current.link;
      temp = previous.info;
   }
}

public void reverse()
{
   Node newList = null;
   Node oldList = head;
   while (oldList != null)
   {
      Node temp = new Node(oldList.info, newList);
      newList = temp;
      oldList = oldList.link;
   }
   head = newList;
}

// in Tree
public int nodeCount()
{
   if (root != null)
      return root.nodeCount();
   else
      return 0;
}

// in Node
int nodeCount()
{
   int leftCount, rightCount;
   if (lChild == null)
      leftCount = 0;
   else
      leftCount = lChild.nodeCount();
   if (rChild == null)
      rightCount = 0;
   else
      rightCount = rChild.nodeCount();
   return 1 + leftCount + rightCount;
}

// in Tree
public int leafCount()
{
   if (root != null)
      return root.leafCount();
   else
      return 0;
}

// in Node
int leafCount()
{
   if (lChild == null && rChild == null)
      return 1;
   else if (lChild == null)
      return rChild.leafCount();
   else if (rChild == null)
      return lChild.leafCount();
   else
      return lChild.leafCount() + rChild.leafCount();
}