public void Add(T node)
{
if (Root == null)
{
Count = 1;
Root = node;
FixTreeOnInsert(node);
return;
}
IRedBlackTreeNode parent = Root;
while (true)
{
if (((IComparable)parent).CompareTo(node) <= 0)
{
if (parent.Left == null)
{
InsertLeft(parent, node);
break;
}
parent = parent.Left;
}
else
{
if (parent.Right == null)
{
InsertRight(parent, node);
break;
}
parent = parent.Right;
}
}
}
void InternalRemove (IRedBlackTreeNode node)
{
if (node.Left != null && node.Right != null) {
IRedBlackTreeNode outerLeft = node.Right.GetOuterLeft ();
InternalRemove (outerLeft);
Replace (node, outerLeft);
outerLeft.Color = node.Color;
outerLeft.Left = node.Left;
if (outerLeft.Left != null)
outerLeft.Left.Parent = outerLeft;
outerLeft.Right = node.Right;
if (outerLeft.Right != null)
outerLeft.Right.Parent = outerLeft;
outerLeft.UpdateAugmentedData ();
return;
}
Count--;
// node has only one child
IRedBlackTreeNode child = node.Left ?? node.Right;
Replace (node, child);
if (node.Color == RedBlackColor.Black && child != null) {
if (child.Color == RedBlackColor.Red) {
child.Color = RedBlackColor.Black;
} else {
DeleteOneChild (child);
}
}
}
public static T GetUncle<T> (this T node) where T : class, IRedBlackTreeNode
{
IRedBlackTreeNode grandparent = node.GetGrandparent ();
if (grandparent == null)
return null;
return (T)(node.Parent == grandparent.Left ? grandparent.Right : grandparent.Left);
}
public static T GetOuterLeft<T> (this T node) where T : class, IRedBlackTreeNode
{
IRedBlackTreeNode result = node;
while (result.Left != null)
result = result.Left;
return (T)result;
}
public void Remove(IRedBlackTreeNode node)
{
if (node.Left != null && node.Right != null)
{
IRedBlackTreeNode outerLeft = node.Right.GetOuterLeft();
InternalRemove(outerLeft);
Replace(node, outerLeft);
outerLeft.Color = node.Color;
outerLeft.Left = node.Left;
if (outerLeft.Left != null)
{
outerLeft.Left.Parent = outerLeft;
}
outerLeft.Right = node.Right;
if (outerLeft.Right != null)
{
outerLeft.Right.Parent = outerLeft;
}
outerLeft.UpdateAugmentedData();
OnNodeRemoved(new RedBlackTreeNodeEventArgs((T)node));
return;
}
InternalRemove(node);
OnNodeRemoved(new RedBlackTreeNodeEventArgs((T)node));
}
static void AppendNode(StringBuilder builder, IRedBlackTreeNode node, int indent)
{
builder.Append(GetIndent(indent) + "Node (" + (node.Color == RedBlackColor.Red ? "r" : "b") + "):" + node + Environment.NewLine);
builder.Append(GetIndent(indent) + "Left: ");
if (node.Left != null)
{
builder.Append(Environment.NewLine);
AppendNode(builder, node.Left, indent + 1);
}
else
{
builder.Append("null");
}
builder.Append(Environment.NewLine);
builder.Append(GetIndent(indent) + "Right: ");
if (node.Right != null)
{
builder.Append(Environment.NewLine);
AppendNode(builder, node.Right, indent + 1);
}
else
{
builder.Append("null");
}
}
public void InsertBefore (IRedBlackTreeNode node, IRedBlackTreeNode newNode)
{
if (node.Left == null) {
InsertLeft (node, newNode);
} else {
InsertRight (node.Left.GetOuterRight (), newNode);
}
}
public static T GetOuterRight<T> (this T node) where T : class, IRedBlackTreeNode
{
IRedBlackTreeNode result = node;
while (result.Right != null) {
result = result.Right;
}
return (T)result;
}
public void InsertRight(IRedBlackTreeNode parentNode, IRedBlackTreeNode newNode)
{
parentNode.Right = newNode;
newNode.Parent = parentNode;
newNode.Color = RedBlackColor.Red;
parentNode.UpdateAugmentedData();
FixTreeOnInsert(newNode);
Count++;
}
public void InsertAfter(IRedBlackTreeNode node, IRedBlackTreeNode newNode)
{
if (node.Right == null)
{
InsertRight(node, newNode);
}
else
{
InsertLeft(node.Right.GetOuterLeft(), newNode);
}
}
void RotateRight (IRedBlackTreeNode node)
{
IRedBlackTreeNode left = node.Left;
Replace (node, left);
node.Left = left.Right;
if (node.Left != null)
node.Left.Parent = node;
left.Right = node;
node.Parent = left;
node.UpdateAugmentedData ();
node.Parent.UpdateAugmentedData ();
}
void RotateLeft (IRedBlackTreeNode node)
{
IRedBlackTreeNode right = node.Right;
Replace (node, right);
node.Right = right.Left;
if (node.Right != null)
node.Right.Parent = node;
right.Left = node;
node.Parent = right;
node.UpdateAugmentedData ();
node.Parent.UpdateAugmentedData ();
}
public static T GetNextNode<T> (this T node) where T : class, IRedBlackTreeNode
{
if (node.Right == null) {
IRedBlackTreeNode curNode = node;
IRedBlackTreeNode oldNode;
do {
oldNode = curNode;
curNode = curNode.Parent;
} while (curNode != null && curNode.Right == oldNode);
return (T)curNode;
}
return (T)node.Right.GetOuterLeft ();
}
void FixTreeOnInsert(IRedBlackTreeNode node)
{
var parent = node.Parent;
if (parent == null)
{
node.Color = RedBlackColor.Black;
return;
}
if (parent.Color == RedBlackColor.Black)
{
return;
}
var uncle = node.GetUncle();
IRedBlackTreeNode grandParent = parent.Parent;
if (uncle != null && uncle.Color == RedBlackColor.Red)
{
parent.Color = RedBlackColor.Black;
uncle.Color = RedBlackColor.Black;
grandParent.Color = RedBlackColor.Red;
FixTreeOnInsert(grandParent);
return;
}
if (node == parent.Right && parent == grandParent.Left)
{
RotateLeft(parent);
node = node.Left;
}
else if (node == parent.Left && parent == grandParent.Right)
{
RotateRight(parent);
node = node.Right;
}
parent = node.Parent;
grandParent = parent.Parent;
parent.Color = RedBlackColor.Black;
grandParent.Color = RedBlackColor.Red;
if (node == parent.Left && parent == grandParent.Left)
{
RotateRight(grandParent);
}
else
{
RotateLeft(grandParent);
}
}
void Replace (IRedBlackTreeNode oldNode, IRedBlackTreeNode newNode)
{
if (newNode != null)
newNode.Parent = oldNode.Parent;
if (oldNode.Parent == null) {
Root = (T)newNode;
} else {
if (oldNode.Parent.Left == oldNode)
oldNode.Parent.Left = newNode;
else
oldNode.Parent.Right = newNode;
oldNode.Parent.UpdateAugmentedData ();
}
}
public static T GetPrevNode <T>(this T node) where T : class, IRedBlackTreeNode <T>
{
if (node.Left == null)
{
IRedBlackTreeNode <T> curNode = node;
IRedBlackTreeNode <T> oldNode;
do
{
oldNode = curNode;
curNode = curNode.Parent;
} while (curNode != null && curNode.Left == oldNode);
return((T)curNode);
}
return((T)node.Left.GetOuterRight());
}
private void AssertNode <T>(T expectedValue, bool expectedIsRed, bool expectedIsLeaf, IRedBlackTreeNode <T> actualNode)
{
Assert.Equal(expectedValue, actualNode.Value);
if (expectedIsRed)
{
Assert.False(actualNode.IsBlack);
Assert.True(actualNode.IsRed);
}
else
{
Assert.True(actualNode.IsBlack);
Assert.False(actualNode.IsRed);
}
if (expectedIsLeaf)
{
Assert.True(actualNode.IsLeaf);
}
else
{
Assert.False(actualNode.IsLeaf);
}
}
void DeleteOneChild(IRedBlackTreeNode node)
{
// case 1
if (node == null || node.Parent == null)
{
return;
}
var parent = node.Parent;
var sibling = node.GetSibling();
if (sibling == null)
{
return;
}
// case 2
if (sibling.Color == RedBlackColor.Red)
{
parent.Color = RedBlackColor.Red;
sibling.Color = RedBlackColor.Black;
if (node == parent.Left)
{
RotateLeft(parent);
}
else
{
RotateRight(parent);
}
sibling = node.GetSibling();
if (sibling == null)
{
return;
}
}
// case 3
if (parent.Color == RedBlackColor.Black && sibling.Color == RedBlackColor.Black && GetColorSafe(sibling.Left) == RedBlackColor.Black && GetColorSafe(sibling.Right) == RedBlackColor.Black)
{
sibling.Color = RedBlackColor.Red;
DeleteOneChild(parent);
return;
}
// case 4
if (parent.Color == RedBlackColor.Red && sibling.Color == RedBlackColor.Black && GetColorSafe(sibling.Left) == RedBlackColor.Black && GetColorSafe(sibling.Right) == RedBlackColor.Black)
{
sibling.Color = RedBlackColor.Red;
parent.Color = RedBlackColor.Black;
return;
}
// case 5
if (node == parent.Left && sibling.Color == RedBlackColor.Black && GetColorSafe(sibling.Left) == RedBlackColor.Red && GetColorSafe(sibling.Right) == RedBlackColor.Black)
{
sibling.Color = RedBlackColor.Red;
if (sibling.Left != null)
{
sibling.Left.Color = RedBlackColor.Black;
}
RotateRight(sibling);
}
else if (node == parent.Right && sibling.Color == RedBlackColor.Black && GetColorSafe(sibling.Right) == RedBlackColor.Red && GetColorSafe(sibling.Left) == RedBlackColor.Black)
{
sibling.Color = RedBlackColor.Red;
if (sibling.Right != null)
{
sibling.Right.Color = RedBlackColor.Black;
}
RotateLeft(sibling);
}
// case 6
sibling = node.GetSibling();
if (sibling == null)
{
return;
}
sibling.Color = parent.Color;
parent.Color = RedBlackColor.Black;
if (node == parent.Left)
{
if (sibling.Right != null)
{
sibling.Right.Color = RedBlackColor.Black;
}
RotateLeft(parent);
}
else
{
if (sibling.Left != null)
{
sibling.Left.Color = RedBlackColor.Black;
}
RotateRight(parent);
}
}
public static bool IsLeaf(this IRedBlackTreeNode node)
{
return(node.Left == null && node.Right == null);
}
static RedBlackColor GetColorSafe(IRedBlackTreeNode node)
{
return(node != null ? node.Color : RedBlackColor.Black);
}