private AStack <int> InitStack()
{
AStack <int> stack = new AStack <int>();
stack.Push(1);
stack.Push(2);
return(stack);
}
/// <summary>
/// A non-recursive method using a stack to remove recursion
/// Will be called by GetEnumerator
/// </summary>
/// <remarks>
/// This method took me a while to get my head around it.
/// Stepping through the code with the debugger helped make it click.
/// </remarks>
/// <returns>An IEnumerator<T></returns>
private IEnumerator <T> InOrderTraversal()
{
if (_head != null)
{
// Used to store nodes we skip
AStack <BinaryTreeNode <T> > stack = new AStack <BinaryTreeNode <T> >();
BinaryTreeNode <T> current = _head;
// When not using recursion, we need to keep track of whether we
// should be processing left or right nodes
bool goLeftNext = true;
// Push the current node on the stack
stack.Push(current);
while (stack.Count > 0)
{
// If heading left
if (goLeftNext)
{
// Push all but the left-most node on the stack
// yield the left-most after this block
while (current.Left != null)
{
stack.Push(current);
current = current.Left;
}
}
// InOrder is left->yield->right
yield return(current.Value);
// If we can go right, do it
if (current.Right != null)
{
current = current.Right;
// Once we've gone right once, start going left again
goLeftNext = true;
}
else
{
// If can't go right, pop off parent node
// so it can be processed and then go to its right side
current = stack.Pop();
goLeftNext = false;
}
}
}
}
public void isEmptyTest()
{
Assert.IsTrue(intStack.IsEmpty());
intStack.Push(2);
Assert.IsFalse(intStack.IsEmpty());
}
