/// <summary>
/// Initializes a new instance of the <see cref="SplayTreeNode{T}"/> class.
/// Constructor.
/// </summary>
/// <param name="data">
/// Values for the node.
/// </param>
/// <param name="left">
/// Left child node.
/// </param>
/// <param name="right">
/// Right child node.
/// </param>
public SplayTreeNode(List <T> data, SplayTreeNode <T> left, SplayTreeNode <T> right)
{
this.Values = data;
NodeList <T> children = new NodeList <T>(2);
children[0] = left;
children[1] = right;
this.Neighbors = children;
if (left.Height > right.Height)
{
this._height = left.Height + 1;
}
else
{
this._height = right.Height + 1;
}
}
/// <summary>
/// Adds element to the tree.
/// </summary>
/// <param name="data">
/// Element to be added.
/// </param>
public override void Add(T data)
{
var dataList = new List <T>(1)
{
data
};
var node = new SplayTreeNode <T>(dataList);
SplayTreeNode <T> current = this._root, parent = null;
int result;
while (current != null)
{
result = this._comparer.Compare(current.Values[0], data);
if (result > 0)
{
parent = current;
current = current.Left;
}
else
{
parent = current;
current = current.Right;
}
}
if (parent == null)
{
this._root = node;
}
else
{
result = this._comparer.Compare(parent.Values[0], data);
if (result > 0)
{
parent.Left = node;
}
else
{
parent.Right = node;
}
}
node.Parent = parent;
this.Splay(node);
}
/// <summary>
/// Indicates whether tree contains element.
/// </summary>
/// <param name="data">
/// Element to be searched.
/// </param>
/// <returns>
/// </returns>
public override SearchResult Contains(T data)
{
SearchResult searchResult;
searchResult.SearchPath = new List <int>();
searchResult.NodesVisited = 0;
SplayTreeNode <T> lastVisited = null;
SplayTreeNode <T> current = this._root;
while (current != null)
{
searchResult.NodesVisited++;
int result = this._comparer.Compare(current.Values[0], data);
if (result == 0)
{
this.Splay(current);
if (searchResult.SearchPath != null)
{
searchResult.SearchPath.Clear();
searchResult.SearchPath = new List <int>();
}
return(searchResult);
}
if (result > 0)
{
lastVisited = current;
current = current.Left;
searchResult.SearchPath.Add(0);
}
else
{
lastVisited = current;
current = current.Right;
searchResult.SearchPath.Add(1);
}
}
this.Splay(lastVisited);
searchResult.SearchPath = null;
return(searchResult);
}
/// <summary>
/// Initializes a new instance of the <see cref="SplayTree{T}"/> class.
/// Basic constructor.
/// </summary>
public SplayTree()
{
this._root = null;
}
/// <summary>
/// Performs Splay operation on input node.
/// </summary>
/// <param name="node">
/// Node to be splayed.
/// </param>
public void Splay(SplayTreeNode <T> node)
{
if (this._root == null || node == null)
{
return;
}
SplayTreeNode <T> current = this._root;
SplayTreeNode <T> parent = null;
while (current != node)
{
if (current == null || current.Neighbors == null)
{
return;
}
int result = this._comparer.Compare(current.Values[0], node.Values[0]);
if (result > 0)
{
if (current.Left != null)
{
parent = current;
current = (SplayTreeNode <T>)current.Left;
}
}
else
{
if (current.Right != null)
{
parent = current;
current = (SplayTreeNode <T>)current.Right;
}
}
}
if (parent == null)
{
return;
}
// ZIG
if (parent.Left == current)
{
parent.Balance(true);
}
// ZAG
else
{
parent.Balance(false);
}
while (current.Parent != null)
{
current = (SplayTreeNode <T>)current.Parent;
}
this._root = current;
if (this._root != node)
{
this.Splay(node);
}
else if (this._root != null)
{
this._root.UpdateHeight();
}
}
/// <summary>
/// Removes element from the tree.
/// </summary>
/// <param name="data">
/// Element to be removed.
/// </param>
/// <returns>
/// The remove.
/// </returns>
public override bool Remove(T data)
{
if (this._root == null)
{
return(false);
}
SplayTreeNode <T> current = this._root, parent = null;
int result = this._comparer.Compare(current.Values[0], data);
while (result != 0)
{
if (result > 0)
{
parent = current;
current = current.Left;
}
else
{
parent = current;
current = current.Right;
}
if (current == null)
{
this.Splay(parent);
return(false);
}
result = this._comparer.Compare(current.Values[0], data);
}
if (current.Right == null)
{
if (parent == null)
{
if (current.Left != null)
{
current.Left.Parent = parent;
}
this._root = current.Left;
}
else
{
result = this._comparer.Compare(parent.Values[0], current.Values[0]);
if (result > 0)
{
if (current.Left != null)
{
current.Left.Parent = parent;
}
parent.Left = current.Left;
}
else
{
if (current.Right != null)
{
current.Right.Parent = parent;
}
parent.Right = current.Right;
}
}
}
else if (current.Right.Left == null)
{
current.Right.Left = current.Left;
if (current.Left != null)
{
current.Left.Parent = current.Right;
}
if (parent == null)
{
if (current.Right != null)
{
current.Right.Parent = parent;
}
this._root = current.Right;
}
else
{
result = this._comparer.Compare(parent.Values[0], current.Values[0]);
if (result > 0)
{
if (current.Right != null)
{
current.Right.Parent = parent;
}
parent.Left = current.Right;
}
else
{
if (current.Right != null)
{
current.Right.Parent = parent;
}
parent.Right = current.Right;
}
}
}
else
{
SplayTreeNode <T> leftMost = current.Right, lmParent = current;
while (leftMost.Left != null)
{
lmParent = leftMost;
leftMost = lmParent.Left;
}
lmParent.Left = leftMost.Right;
leftMost.Left = current.Left;
leftMost.Right = current.Right;
if (lmParent.Left != null)
{
lmParent.Left.Parent = leftMost;
}
if (leftMost.Right != null)
{
leftMost.Right.Parent = lmParent;
}
if (current.Left != null)
{
current.Left.Parent = leftMost;
}
if (current.Right != null)
{
current.Right.Parent = leftMost;
}
if (parent == null)
{
leftMost.Parent = parent;
this._root = leftMost;
}
else
{
result = this._comparer.Compare(parent.Values[0], current.Values[0]);
if (result > 0)
{
leftMost.Parent = parent;
parent.Left = leftMost;
}
else
{
leftMost.Parent = parent;
parent.Right = leftMost;
}
}
}
if (current != null)
{
this.Splay((SplayTreeNode <T>)current.Parent);
}
current.Parent = current.Left = current.Right = null;
return(true);
}
/// <summary>
/// Clears nodes of the tree.
/// </summary>
public override void Clear()
{
this._root = null;
}
/// <summary>
/// Performs left or right rotation.
/// </summary>
/// <param name="leftBalance">
/// Indicates whether perform left rotation.
/// </param>
public void Balance(bool leftBalance)
{
if (leftBalance)
{
// right rotation
SplayTreeNode <T> z = this;
SplayTreeNode <T> y = this.Left;
SplayTreeNode <T> a = this.Left.Left;
SplayTreeNode <T> b = this.Left.Right;
SplayTreeNode <T> c = this.Right;
bool zIsleftNode = false;
if (z.Parent != null && ((SplayTreeNode <T>)z.Parent).Left == this)
{
zIsleftNode = true;
}
z.Left = b;
if (b != null)
{
b.Parent = z;
}
y.Right = z;
if (y != null)
{
y.Parent = z.Parent;
if (y.Parent != null)
{
if (zIsleftNode)
{
((SplayTreeNode <T>)y.Parent).Left = y;
}
else
{
((SplayTreeNode <T>)y.Parent).Right = y;
}
}
}
z.Parent = y;
}
else
{
// left rotation
SplayTreeNode <T> z = this;
SplayTreeNode <T> y = this.Right;
SplayTreeNode <T> a = this.Left;
SplayTreeNode <T> b = this.Right.Left;
SplayTreeNode <T> c = this.Right.Right;
bool zIsleftNode = false;
if (z.Parent != null && ((SplayTreeNode <T>)z.Parent).Left == this)
{
zIsleftNode = true;
}
z.Right = b;
if (b != null)
{
b.Parent = z;
}
y.Left = z;
if (y != null)
{
y.Parent = z.Parent;
if (y.Parent != null)
{
if (zIsleftNode)
{
((SplayTreeNode <T>)y.Parent).Left = y;
}
else
{
((SplayTreeNode <T>)y.Parent).Right = y;
}
}
}
z.Parent = y;
}
}
/// <summary>
/// Balances node.
/// </summary>
/// <returns>
/// The balance.
/// </returns>
public bool Balance()
{
this.UpdateHeight();
int leftHeight = 0;
int rightHeight = 0;
if (this.Left != null)
{
leftHeight = this.Left.Height;
}
if (this.Right != null)
{
rightHeight = this.Right.Height;
}
if (leftHeight - rightHeight > 1)
{
// right rotation
SplayTreeNode <T> z = this;
SplayTreeNode <T> y = this.Left;
SplayTreeNode <T> a = this.Left.Left;
SplayTreeNode <T> b = this.Left.Right;
SplayTreeNode <T> c = this.Right;
bool zIsleftNode = false;
if (z.Parent != null && ((SplayTreeNode <T>)z.Parent).Left == this)
{
zIsleftNode = true;
}
z.Left = b;
if (b != null)
{
b.Parent = z;
}
y.Right = z;
if (y != null)
{
y.Parent = z.Parent;
if (y.Parent != null)
{
if (zIsleftNode)
{
((SplayTreeNode <T>)y.Parent).Left = y;
}
else
{
((SplayTreeNode <T>)y.Parent).Right = y;
}
}
}
z.Parent = y;
return(true);
}
else if (rightHeight - leftHeight > 1)
{
// left rotation
SplayTreeNode <T> z = this;
SplayTreeNode <T> y = this.Right;
SplayTreeNode <T> a = this.Left;
SplayTreeNode <T> b = this.Right.Left;
SplayTreeNode <T> c = this.Right.Right;
bool zIsleftNode = false;
if (z.Parent != null && ((SplayTreeNode <T>)z.Parent).Left == this)
{
zIsleftNode = true;
}
z.Right = b;
if (b != null)
{
b.Parent = z;
}
y.Left = z;
if (y != null)
{
y.Parent = z.Parent;
if (y.Parent != null)
{
if (zIsleftNode)
{
((SplayTreeNode <T>)y.Parent).Left = y;
}
else
{
((SplayTreeNode <T>)y.Parent).Right = y;
}
}
}
z.Parent = y;
return(true);
}
bool balanced = false;
if (this.Left != null && this.Left.Balance())
{
balanced = true;
}
if (this.Right != null && this.Right.Balance())
{
balanced = true;
}
return(balanced);
}