public RBTreeNode FindNode(int value)
{
RBTreeNode node = Root;
while (IsNil(node))
{
if (node.Value == value)
{
return(node);
}
if (value <= node.Value)
{
node = node.Left;
}
else
{
node = node.Right;
}
}
return(null);
}
public Nil(RBTreeNode parent)
{
Value = 0;
Color = RBTreeNodeColors.Black;
Parent = parent;
}
private void FixDeledTreeBalance(RBTreeNode delNode)
{
if (delNode == null || delNode.Parent == null)
{
return;
}
RBTreeNode fahter = delNode.Parent;
RBTreeNode bro = fahter.Left;
bool isLeft = (fahter.Left == delNode);
if (delNode == fahter.Left)
{
bro = delNode.Parent.Right;
}
//Case 1: father is red
if (fahter.Color == RBTreeNodeColors.Red)
{
fahter.Color = RBTreeNodeColors.Black;
bro.Color = RBTreeNodeColors.Red;
return;
}
//Case 2:parent is black,brother is red
if (bro.Color == RBTreeNodeColors.Red)
{
fahter.Color = RBTreeNodeColors.Red;
bro.Color = RBTreeNodeColors.Black;
if (isLeft)
{
LeftRotation(fahter);
}
else
{
RightRotation(fahter);
}
return;
}
//case 3： parent is black,brohter is black,brother right is red
if (bro.Right != null && bro.Right.Color == RBTreeNodeColors.Red)
{
LeftRotation(bro);
FixDeledTreeBalance(delNode);
return;
}
//case 4： parent is black,brohter is black,brother left is red
if (bro.Left != null && bro.Left.Color == RBTreeNodeColors.Red)
{
RightRotation(bro);
FixDeledTreeBalance(delNode);
return;
}
//case 5： parent is black,brohter is black,sons of brother is black
bro.Color = RBTreeNodeColors.Red;
FixDeledTreeBalance(fahter);
}
private bool IsNil(RBTreeNode node)
{
return(node is Nil);
}
private void RB_Delete_Fixup(RBTreeNode x)
{
RBTreeNode bro = null;
while (x != Root && x.Color == RBTreeNodeColors.Black)
{
if (x == x.Parent.Left)
{
bro = x.Parent.Right;
if (bro.Color == RBTreeNodeColors.Red)
{
bro.Color = RBTreeNodeColors.Black;
x.Parent.Color = RBTreeNodeColors.Red;
LeftRotation(x.Parent);
bro = x.Parent.Right;
}
if (bro.Left.Color == RBTreeNodeColors.Black &&
bro.Right.Color == RBTreeNodeColors.Black)
{
bro.Color = RBTreeNodeColors.Red;
x = x.Parent;
}
else
{
if (bro.Left.Color == RBTreeNodeColors.Red)
{
bro.Left.Color = RBTreeNodeColors.Black;
bro.Color = RBTreeNodeColors.Red;
RightRotation(bro);
bro = x.Parent.Right;
}
bro.Color = x.Parent.Color;
x.Parent.Color = RBTreeNodeColors.Black;
bro.Right.Color = RBTreeNodeColors.Black;
LeftRotation(x.Parent);
x = Root;
}
}
else
{
bro = x.Parent.Left;
if (bro.Color == RBTreeNodeColors.Red)
{
bro.Color = RBTreeNodeColors.Black;
x.Parent.Color = RBTreeNodeColors.Red;
RightRotation(x.Parent);
bro = x.Parent.Left;
}
if (bro.Left.Color == RBTreeNodeColors.Black &&
bro.Right.Color == RBTreeNodeColors.Black)
{
bro.Color = RBTreeNodeColors.Red;
x = x.Parent;
}
else
{
if (bro.Right.Color == RBTreeNodeColors.Red)
{
bro.Left.Color = RBTreeNodeColors.Black;
bro.Color = RBTreeNodeColors.Red;
LeftRotation(bro);
bro = x.Parent.Right;
}
bro.Color = x.Parent.Color;
x.Parent.Color = RBTreeNodeColors.Black;
bro.Right.Color = RBTreeNodeColors.Black;
RightRotation(x.Parent);
x = Root;
}
}
}
x.Color = RBTreeNodeColors.Black;
}
