internal BinarySearchTreeNode(TEntity value, BinarySearchTreeNode <TEntity> parent)
{
Value = value;
Parent = parent;
}
public void Delete(TEntity value)
{
BinarySearchTreeNode <TEntity> node = FindNode(value);
if (node == null)
{
throw new EntityNotExistsInBinarySearchTreeException();
}
BinarySearchTreeNode <TEntity> parent = null;
BinarySearchTreeNode <TEntity> child = null;
// First case when node doesn't have children
if (node.Left == null && node.Right == null)
{
parent = node.Parent;
}
//Second case when node has only one children
else if (node.Left == null || node.Right == null)
{
parent = node.Parent;
child = node.Left == null
? node.Right
: node.Left;
}
// Third case - node has two children
else
{
BinarySearchTreeNode <TEntity> successorNode = GetSuccessorNode(node);
// Successor for node with two children always doesn't have left node
// We change node value with successor value and connect successor parent with successor right child
parent = successorNode.Parent;
child = successorNode.Right;
node.Value = successorNode.Value;
}
// change parent
if (child != null)
{
child.Parent = parent;
}
// change child node
if (parent == null)
{
_root = child;
}
else
{
if (parent.Value.CompareTo(node.Value) > 0)
{
parent.Left = child;
}
else
{
parent.Right = child;
}
}
_size--;
}
