Example #1
0
        /*******************************************************************************************/
        /*******************************************************************************************/

        private void DeleteNodeLeaf(Node node)
        {
            if (node.Color == NodeColor.RED)
            {
                DetachNode(node);
            }
            else
            {
                NodeDoubleBlack nodeDB = new NodeDoubleBlack(node.Parent, node, null);
                DetachNode(node);
                FixDoubleBlackNode(nodeDB);
            }
        }
Example #2
0
        /*******************************************************************************************/
        /*******************************************************************************************/

        private void FixDoubleBlackNode(NodeDoubleBlack nodeDB)
        {
            if (nodeDB.Parent is null)
            {
                return;
            }

            Node sibling = nodeDB.Sibling;

            if (sibling != null && sibling.Color == NodeColor.BLACK && HasRedNode(sibling))
            {
                Node siblingRedChild = HasLeftNodeRed(sibling) ? sibling.Left : sibling.Right;

                if (sibling < sibling.Parent &&
                    (HasBothNodesRed(sibling) || HasLeftNodeRed(sibling)))
                {
                    // Left Left case
                    SetNodeColor(sibling.Left, NodeColor.BLACK);
                    SwapColors(sibling, sibling.Parent);
                    RotateNode(sibling);
                }
                else if (sibling < sibling.Parent && siblingRedChild > sibling)
                {
                    // Left Right Case
                    SwapColors(siblingRedChild, sibling);
                    RotateNode(siblingRedChild);
                    RotateNode(siblingRedChild);
                }
                else if ((sibling > sibling.Parent && siblingRedChild > sibling) ||
                         HasBothNodesRed(sibling))
                {
                    // Right Right Case
                    RotateNode(sibling);
                    SwapColors(sibling, sibling.Parent);
                }
                else if (sibling > sibling.Parent && HasLeftNodeRed(sibling))
                {
                    // Left Right Case
                    RotateNode(sibling.Left);
                    RotateNode(sibling.Left);
                }
            }
            else if (sibling is null ||
                     (sibling.Color == NodeColor.BLACK && HasBothNodesBlack(sibling)))
            {
                // Recolour
                if (nodeDB.Parent.Color == NodeColor.BLACK && sibling != null)
                {
                    SetNodeColor(sibling, NodeColor.RED);
                }
            }
Example #3
0
        /*******************************************************************************************/
        /*******************************************************************************************/

        private void DeleteNodeWithOneChild(Node node)
        {
            Node child = node.Left is null ? node.Right : node.Left;

            if (node.Color == NodeColor.RED || child.Color == NodeColor.RED)
            {
                SetNodeColor(child, NodeColor.BLACK);
                DetachNode(node);
            }
            else
            {
                NodeDoubleBlack nodeDB = new NodeDoubleBlack(node.Parent, node, child);
                DetachNode(node);
                FixDoubleBlackNode(nodeDB);
            }
        }
Example #4
0
        /*******************************************************************************************/
        /*******************************************************************************************/

        private void DeleteNodeWithBothChildren(Node node)
        {
            Node leastSuccessor      = FindLowestNode(node.Right);
            Node leastSuccessorChild = leastSuccessor.Right is null ? null : leastSuccessor.Right;

            if (leastSuccessor.Color == NodeColor.RED ||
                (leastSuccessorChild != null && leastSuccessorChild.Color == NodeColor.RED))
            {
                if (leastSuccessorChild != null)
                {
                    SetNodeColor(leastSuccessorChild, NodeColor.BLACK);
                }
                SwapColors(node, leastSuccessor);
                DetachNode(node);
            }
            else
            {
                NodeDoubleBlack nodeDB = new NodeDoubleBlack(leastSuccessor.Parent, leastSuccessor, leastSuccessorChild);
                SwapColors(node, leastSuccessor);
                DetachNode(node);
                FixDoubleBlackNode(nodeDB);
            }
        }