public BinarySearchTree()
{
this.head = null;
}
public BinaryNode(BinaryNode left, BinaryNode right, int value)
{
this.left = left;
this.right = right;
this.val = value;
}
/// <summary>
/// Delete the specified val.
/// </summary>
/// <returns>The delete.</returns>
/// <param name="val">Value.</param>
public void Delete(int val)
{
if (head == null)
{
Console.WriteLine("The root is null dawg");
return;
}
BinaryNode theParent = null, theIter = head;
bool isLeft = false;
/*
* Finds the node to be deleted
*/
while (theIter != null && theIter.Value != val)
{
theParent = theIter;
if (theIter.Value > val)
{
theIter = theIter.Left;
isLeft = true;
}
else
{
theIter = theIter.Right;
isLeft = false;
}
if (theIter == null)
{
Console.WriteLine("Your value ain't here");
return;
}
}
/*
* The following readjusts the pointers
*/
//CASE 1: IF THE ITER HAS NO RIGHT CHILD, THEN THE ITER'S LEFT CHILD BECOMES POINTED AT BY THE PARENT
if (theIter.Right == null)
{
if (theParent == null)
{
head = theIter.Left;
}
else
{
if (isLeft)
{
theParent.Left = theIter.Left;
}
else
{
theParent.Right = theIter.Left;
}
}
//CASE 2: If iter's right child has no left child, then iter's right child replaces iter in the tree
}
else if (theIter.Right.Left == null)
{
theIter.Right.Left = theIter.Left;
if (theParent == null)
{
head = theIter.Right;
}
else
{
if (isLeft)
{
theParent.Left = theIter.Right;
}
else
{
theParent.Right = theIter.Right;
}
}
//CASE 3: If current's right child has a left child, replace current with current's right child's left-most descendent
}
else
{
BinaryNode leftMost = theIter.Right.Left, lmParent = theIter.Right;
while (leftMost.Left != null)
{
lmParent = leftMost;
leftMost = leftMost.Left;
}
lmParent.Left = leftMost.Right;
leftMost.Left = theIter.Left;
leftMost.Right = theIter.Right;
if (theParent == null)
{
head = leftMost;
}
else
{
if (isLeft)
{
theParent.Left = leftMost;
}
else
{
theParent.Right = leftMost;
}
}
}
}
public BinaryNode(int value)
{
this.val = value;
this.left = null;
this.right = null;
}