private void RebalancePostDeletion(RBTreeNode node)
{
// Very similar to RebalancePostInsertion function
// node is the node in the location of/closest to the node just deleted
RBTreeNode s; // represents sibbling of node
while (node != Root && node.IsBlack())
{
if (node == node.Parent().Left())
{
s = node.Parent().Right();
if (s.IsRed()) // case 1
{
s.SetBlack();
node.Parent().SetRed();
RotateLeft(node.Parent());
s = node.Parent().Right();
}
if (s.Left().IsBlack() && s.Right().IsBlack()) // case 2
{
s.SetRed();
node = node.Parent();
}
else
{
if (s.Right().IsBlack()) // case 3
{
s.Left().SetBlack();
s.SetRed();
RotateRight(s);
s = node.Parent().Right();
}
if (s.Parent().IsRed())
{
s.SetRed();
}
else
{
s.SetBlack();
}
node.Parent().SetBlack();
s.Right().SetBlack();
RotateLeft(s.Parent());
node = Root;
}
}
else
{
s = node.Parent().Left();
if (s.IsRed())
{
s.SetBlack();
node.Parent().SetRed();
RotateRight(node.Parent());
s = node.Parent().Left();
}
if (s.Right() == null)
{
s.SetRight(Leaf);
}
if (s.Left() == null)
{
s.SetLeft(Leaf);
}
if (s.Right().IsBlack() && s.Left().IsBlack())
{
s.SetRed();
node = node.Parent();
}
else
{
if (s.Left().IsBlack())
{
s.Right().SetBlack();
s.SetRed();
RotateLeft(s);
s = node.Parent().Left();
}
if (s.Parent().IsRed())
{
s.SetRed();
}
else
{
s.SetBlack();
}
node.Parent().SetBlack();
s.Left().SetBlack();
RotateRight(node.Parent());
node = Root;
}
}
}
node.SetBlack();
}
