/// <summary> Find an item in the tree.</summary>
/// <param name="x">the item to search for.
/// </param>
/// <returns> the matching item of null if not found.
/// </returns>
public virtual Comparable find(Comparable x)
{
AANode current = root;
nullNode.element = x;
for (; ;)
{
if (x.compareTo(current.element) < 0)
{
current = current.left;
}
else if (x.compareTo(current.element) > 0)
{
current = current.right;
}
else if (current != nullNode)
{
return(current.element);
}
else
{
return(null);
}
}
}
public AANode(Comparable theElement, AANode lt, AANode rt)
{
element = theElement;
left = lt;
right = rt;
level = 1;
}
static AATree()
{
{
nullNode = new AANode(null);
nullNode.left = nullNode.right = nullNode;
nullNode.level = 0;
}
}
/// <summary> Rotate binary tree node with right child.</summary>
internal static AANode rotateWithRightChild(AANode k1)
{
AANode k2 = k1.right;
k1.right = k2.left;
k2.left = k1;
return(k2);
}
/// <summary> Rotate binary tree node with left child.</summary>
internal static AANode rotateWithLeftChild(AANode k2)
{
AANode k1 = k2.left;
k2.left = k1.right;
k1.right = k2;
return(k1);
}
/// <summary> Skew primitive for AA-trees.</summary>
/// <param name="t">the node that roots the tree.
/// </param>
/// <returns> the new root after the rotation.
/// </returns>
private AANode skew(AANode t)
{
if (t.left.level == t.level)
{
t = rotateWithLeftChild(t);
}
return(t);
}
/// <summary> Split primitive for AA-trees.</summary>
/// <param name="t">the node that roots the tree.
/// </param>
/// <returns> the new root after the rotation.
/// </returns>
private AANode split(AANode t)
{
if (t.right.right.level == t.level)
{
t = rotateWithRightChild(t);
t.level++;
}
return(t);
}
/// <summary> Internal method to print a subtree in sorted order.</summary>
/// <param name="t">the node that roots the tree.
/// </param>
private void printTree(AANode t)
{
if (t != t.left)
{
printTree(t.left);
//UPGRADE_TODO: The equivalent in .NET for method 'java.lang.Object.toString' may return a different value. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1043'"
System.Console.Out.WriteLine(t.element.ToString());
printTree(t.right);
}
}
/// <summary> Find the largest item in the tree.</summary>
/// <returns> the largest item or null if empty.
/// </returns>
public virtual Comparable findMax()
{
if (Empty)
{
return(null);
}
AANode ptr = root;
while (ptr.right != nullNode)
{
ptr = ptr.right;
}
return(ptr.element);
}
/// <summary> Internal method to remove from a subtree.</summary>
/// <param name="x">the item to remove.
/// </param>
/// <param name="t">the node that roots the tree.
/// </param>
/// <returns> the new root.
/// </returns>
private AANode remove(Comparable x, AANode t)
{
if (t != nullNode)
{
// Step 1: Search down the tree and set lastNode and deletedNode
lastNode = t;
if (x.compareTo(t.element) < 0)
{
t.left = remove(x, t.left);
}
else
{
deletedNode = t;
t.right = remove(x, t.right);
}
// Step 2: If at the bottom of the tree and
// x is present, we remove it
if (t == lastNode)
{
if (deletedNode == nullNode || x.compareTo(deletedNode.element) != 0)
{
return(t); // Item not found; do nothing
}
deletedNode.element = t.element;
t = t.right;
}
// Step 3: Otherwise, we are not at the bottom; rebalance
else if (t.left.level < t.level - 1 || t.right.level < t.level - 1)
{
if (t.right.level > --t.level)
{
t.right.level = t.level;
}
t = skew(t);
t.right = skew(t.right);
t.right.right = skew(t.right.right);
t = split(t);
t.right = split(t.right);
}
}
return(t);
}
/// <summary> Internal method to insert into a subtree.</summary>
/// <param name="x">the item to insert.
/// </param>
/// <param name="t">the node that roots the tree.
/// </param>
/// <returns> the new root.
/// </returns>
private AANode insert(Comparable x, AANode t)
{
if (t == nullNode)
{
t = new AANode(x, nullNode, nullNode);
}
else if (x.compareTo(t.element) < 0)
{
t.left = insert(x, t.left);
}
else if (x.compareTo(t.element) > 0)
{
t.right = insert(x, t.right);
}
else
{
return(t);
}
t = skew(t);
t = split(t);
return(t);
}
