a) List the order in which the nodes are visited in: 
post-order.
![](Pasted%20image%2020240319225420.png)
D,B,F,G,E,C,A

pre-order
A,B,D,C,E,F,G

in-order
D,B,F,E,G,C,A

b)
```java
public class BinTreeNode
{
	public String info;
	public BinTreeNode leftChild, rightChild;
}
```

```java
public void postTraverse( BinTreeNode node )
{
	if ( node != null )
	{
		postTraverse( node.leftNode );
		postTraverse( node.rightNode );
		System.out.println( node.info );
	}
}
```

c) The following method counts the number of nodes in the tree
```java
public int countTree(BinTreeNode t)
{
	int count;
	if (t == null)
		count = 0
	else
		count = countTree(t.leftChild)+countTree(t.rightChild)+1;
	return count;
}
```
![](Pasted%20image%2020240319234142.png)

countTree(root)
-> count = countTree(t.leftChild) + countTree(t.rightChild+1)
countTree(t.leftChild)
-> return 1, since left and right child null
countTree(t.rightChild)
-> return 1, since left and right child null
count = 1 + 1 + 1 = 3