private void RotateRight(RedBLackNode <TKey, TValue> node)
{
var current = node.Left;
node.Left = current.Right;
if (!current.Right.IsLeaf)
{
current.Right.Parent = node;
}
current.Parent = node.Parent;
if (node.Parent.IsLeaf)
{
_root = current;
}
else
{
if (node == node.Parent.Right)
{
node.Parent.Right = current;
}
else
{
node.Parent.Left = current;
}
}
current.Right = node;
node.Parent = current;
}
private void BalanceAfterAddition(RedBLackNode <TKey, TValue> node)
{
while (node.Parent.Color == NodeColor.Red)
{
if (node.Parent == node.Parent.Parent.Left)
{
var uncle = node.Parent.Parent.Right;
if (uncle.Color == NodeColor.Red)
{
node.Parent.Color = NodeColor.Black;
uncle.Color = NodeColor.Black;
node.Parent.Parent.Color = NodeColor.Red;
node = node.Parent.Parent;
}
else
{
if (node == node.Parent.Right)
{
node = node.Parent;
RotateLeft(node);
}
node.Parent.Color = NodeColor.Black;
node.Parent.Parent.Color = NodeColor.Red;
RotateRight(node.Parent.Parent);
}
}
else
{
var uncle = node.Parent.Parent.Left;
if (uncle.Color == NodeColor.Red)
{
node.Parent.Color = NodeColor.Black;
uncle.Color = NodeColor.Black;
node.Parent.Parent.Color = NodeColor.Red;
node = node.Parent.Parent;
}
else
{
if (node == node.Parent.Left)
{
node = node.Parent;
RotateRight(node);
}
node.Parent.Color = NodeColor.Black;
node.Parent.Parent.Color = NodeColor.Red;
RotateLeft(node.Parent.Parent);
}
}
}
_root.Color = NodeColor.Black;
}
private List <KeyValuePair <TKey, TValue> > Traverse(RedBLackNode <TKey, TValue> node)
{
var nodes = new List <KeyValuePair <TKey, TValue> >();
if (!node.IsLeaf)
{
nodes.AddRange(Traverse(node.Left));
nodes.Add(new KeyValuePair <TKey, TValue>(node.Key, node.Value));
nodes.AddRange(Traverse(node.Right));
}
return(nodes);
}
public void Add(TKey key, TValue value)
{
var node = new RedBLackNode <TKey, TValue>(key, value);
var parent = new RedBLackNode <TKey, TValue>();
var current = _root;
while (!current.IsLeaf)
{
parent = current;
if (node.Key.CompareTo(current.Key) < 0)
{
current = current.Left;
}
else if (node.Key.CompareTo(current.Key) > 0)
{
current = current.Right;
}
else
{
throw new ArgumentException("Item with same key has already been added");
}
}
node.Parent = parent;
if (parent.IsLeaf)
{
_root = node;
}
else if (node.Key.CompareTo(parent.Key) < 0)
{
parent.Left = node;
}
else
{
parent.Right = node;
}
node.Left = new RedBLackNode <TKey, TValue>();
node.Right = new RedBLackNode <TKey, TValue>();
node.Color = NodeColor.Red;
Count++;
BalanceAfterAddition(node);
}
private RedBLackNode <TKey, TValue> Find(TKey key, RedBLackNode <TKey, TValue> node)
{
if (node.IsLeaf || key.CompareTo(node.Key) == 0)
{
return(node);
}
else
{
if (key.CompareTo(node.Key) < 0)
{
return(Find(key, node.Left));
}
else
{
return(Find(key, node.Right));
}
}
}
private RedBLackNode <TKey, TValue> Successor(RedBLackNode <TKey, TValue> node)
{
if (!node.Right.IsLeaf)
{
node = node.Right;
while (!node.Left.IsLeaf)
{
node = node.Left;
}
return(node);
}
var parent = node.Parent;
while (!parent.IsLeaf && node == parent.Right)
{
node = parent;
parent = parent.Parent;
}
return(parent);
}
public RedBlackTree()
{
_root = new RedBLackNode <TKey, TValue>();
Count = 0;
}
public void Clear()
{
_root = new RedBLackNode <TKey, TValue>();
Count = 0;
}
private void BalanceAfterRemoving(RedBLackNode <TKey, TValue> node)
{
while (node != _root && node.Color == NodeColor.Black)
{
if (node == node.Parent.Left)
{
var current = node.Parent.Right;
if (current.Color == NodeColor.Red)
{
current.Color = NodeColor.Black;
node.Parent.Color = NodeColor.Red;
RotateLeft(node.Parent);
current = node.Parent.Right;
}
if (current.Left.Color == NodeColor.Black && current.Right.Color == NodeColor.Black)
{
current.Color = NodeColor.Red;
node = node.Parent;
}
else
{
if (current.Right.Color == NodeColor.Black)
{
current.Left.Color = NodeColor.Black;
current.Color = NodeColor.Red;
RotateRight(current);
current = node.Parent.Right;
}
current.Color = node.Parent.Color;
node.Parent.Color = NodeColor.Black;
current.Right.Color = NodeColor.Black;
RotateLeft(node.Parent);
node = _root;
}
}
else
{
var current = node.Parent.Left;
if (current.Color == NodeColor.Red)
{
current.Color = NodeColor.Black;
node.Parent.Color = NodeColor.Red;
RotateRight(node.Parent);
current = node.Parent.Left;
}
if (current.Left.Color == NodeColor.Black && current.Right.Color == NodeColor.Black)
{
current.Color = NodeColor.Red;
node = node.Parent;
}
else
{
if (current.Left.Color == NodeColor.Black)
{
current.Right.Color = NodeColor.Black;
current.Color = NodeColor.Red;
RotateLeft(current);
current = node.Parent.Left;
}
current.Color = node.Parent.Color;
node.Parent.Color = NodeColor.Black;
current.Left.Color = NodeColor.Black;
RotateRight(node.Parent);
node = _root;
}
}
}
node.Color = NodeColor.Black;
}
public bool Remove(TKey key)
{
var node = Find(key, _root);
if (node.IsLeaf)
{
return(false);
}
Count--;
RedBLackNode <TKey, TValue> linkedNode;
RedBLackNode <TKey, TValue> workNode;
if (node.Left.IsLeaf || node.Right.IsLeaf)
{
workNode = node;
}
else
{
workNode = Successor(node);
}
if (!workNode.Left.IsLeaf)
{
linkedNode = workNode.Left;
}
else
{
linkedNode = workNode.Right;
}
linkedNode.Parent = workNode.Parent;
if (workNode.Parent.IsLeaf)
{
_root = linkedNode;
}
else
{
if (workNode == workNode.Parent.Left)
{
workNode.Parent.Left = linkedNode;
}
else
{
workNode.Parent.Right = linkedNode;
}
}
if (workNode != node)
{
node.Key = workNode.Key;
node.Value = workNode.Value;
}
if (workNode.Color == NodeColor.Black)
{
BalanceAfterRemoving(linkedNode);
}
return(true);
}