/// <summary>
/// Finds the min node in the subtree and returns the root of the new subtree
/// </summary>
private BinarySearchTreeNode <T> FindAndRemoveMin(BinarySearchTreeNode <T> subtreeRoot, ref BinarySearchTreeNode <T> min)
{
if (subtreeRoot.Left == null)
{
if (subtreeRoot.Right == null)
{
min = subtreeRoot;
return(null);
}
else
{
min = subtreeRoot;
return(subtreeRoot.Right);
}
}
var curNode = subtreeRoot;
var lastNode = subtreeRoot;
while (curNode.Left != null)
{
lastNode = curNode;
curNode = curNode.Left;
}
lastNode.Left = curNode.Right;
min = curNode;
return(subtreeRoot);
}
/// <summary>
/// Removes an element from the <see cref="BinarySearchTree{T}"/>.
/// </summary>
/// <param name="value">The value to remove.</param>
/// <returns>true if the item is successfully removed; otherwise false. Also returns false if item is not found.</returns>
public virtual bool Remove(T value)
{
if (Root == null)
{
return(false);
}
var curNode = Root;
var lastNode = Root;
bool lastWasLeftSide = true;
while (curNode != null)
{
int cmp = comparer.Compare(value, curNode.Value);
if (cmp < 0)
{
lastNode = curNode;
curNode = curNode.Left;
lastWasLeftSide = true;
}
else if (cmp > 0)
{
lastNode = curNode;
curNode = curNode.Right;
lastWasLeftSide = false;
}
else
{
if (curNode.Right == null)
{
if (lastWasLeftSide)
{
if (curNode == Root)
{
Root = curNode.Left;
}
else
{
lastNode.Left = curNode.Left;
}
}
else
{
lastNode.Right = curNode.Left;
}
}
else
{
BinarySearchTreeNode <T> min = null;
var rightNode = FindAndRemoveMin(curNode.Right, ref min);
min.Right = rightNode;
min.Left = curNode.Left;
if (lastWasLeftSide)
{
if (curNode == Root)
{
Root = min;
}
else
{
lastNode.Left = min;
}
}
else
{
lastNode.Right = min;
}
}
curNode.Invalidate();
Count--;
return(true);
}
}
return(false);
}