/// <summary>
/// Enables the user to find a node based on the user input, 'val'
/// </summary>
/// <param name="val">value that the program is looking for in the tree</param>
/// <returns></returns>
public T Find(T val)
{
RedBlackNode <T> temp = _root;
while (temp != null)
{
if (temp.Data.CompareTo(val) == 0)
{
return(temp.Data);
}
else if (temp.Data.CompareTo(val) > 0)
{
temp = temp.RightChild;
}
else
{
temp = temp.LeftChild;
}
}
return(default(T));
}
/// <summary>
/// Adds a new RedBlackNode in the correct location
/// </summary>
/// <param name="val">node that contains the data</param>
public void Add(T val)
{
RedBlackNode <T> node = new RedBlackNode <T>(val, null, null, null, false);
if (_root == null)
{
_root = node;
return;
}
RedBlackNode <T> root = _root;
RedBlackNode <T> newNode = null;
while (root != null)
{
int comparison = val.CompareTo(root.Data);
if (comparison > 0)
{
if (root.RightChild == null)
{
newNode = new RedBlackNode <T>(val, null, null, root, true);//false or true?
root.RightChild = newNode;
FixColors(newNode);
break;
}
root = root.RightChild;
}
else
{
if (root.LeftChild == null)
{
newNode = new RedBlackNode <T>(val, null, null, root, true);//false or true?
root.LeftChild = newNode;
FixColors(newNode);
break;
}
root = root.LeftChild;
}
}
}
/// <summary>
/// Gets the information associated with the given name in the given binary search tree.
/// If the given name is not in the tree, returns a NameInformation with a null name.
/// </summary>
/// <param name="name">The name to look for.</param>
/// <param name="t">The binary search tree to look in.</param>
/// <returns>The NameInformation containing the given name, or a NameInformation with a null name
/// if the tree does not contain the name.</returns>
private NameInformation GetInformation(string name, RedBlackNode <NameInformation> t)
{
if (t == null)
{
return(new NameInformation());
}
else
{
int comp = name.CompareTo(t.Data.Name);
if (comp == 0)
{
return(t.Data);
}
else if (comp < 0)
{
return(GetInformation(name, t.LeftChild));
}
else
{
return(GetInformation(name, t.RightChild));
}
}
}
/// <summary>
/// recolors and rebalances the tree
/// </summary>
/// <param name="lol"> newly added node</param>
private void FixColors(RedBlackNode <T> node)
{
RedBlackNode <T> uncle = null;
RedBlackNode <T> newNode = node;
while (newNode != _root && newNode.Parent.Red && newNode.Red)
{
if (newNode.Parent == newNode.Parent.Parent.LeftChild)
{
uncle = newNode.Parent.Parent.RightChild;
}
else if (newNode.Parent == newNode.Parent.Parent.RightChild)
{
uncle = newNode.Parent.Parent.LeftChild;
}
if (newNode.Parent.Parent.RightChild != null && newNode.Parent.Parent.LeftChild != null && uncle.Red)
{
if (uncle == newNode.Parent.Parent.RightChild)
{
newNode.Parent.Parent.Red = true;
newNode.Parent.Red = false;
newNode.Parent.Parent.RightChild.Red = false;
}
else
{
newNode.Parent.Parent.Red = true;
newNode.Parent.Red = false;
newNode.Parent.Parent.LeftChild.Red = false;
}
newNode = newNode.Parent.Parent;
}
else if (uncle == null || uncle.Red == false)
{
if (newNode == newNode.Parent.LeftChild && newNode.Parent == newNode.Parent.Parent.LeftChild)
{
RotateRight(newNode.Parent.Parent);
newNode.Red = true;
newNode.Parent.Red = false;
newNode.Parent.RightChild.Red = true;
if (newNode.Parent.RightChild.RightChild != null)
{
newNode.Parent.RightChild.RightChild.Red = false;
}
}
else if (newNode == newNode.Parent.RightChild && newNode.Parent == newNode.Parent.Parent.RightChild)
{
RotateLeft(newNode.Parent.Parent); //exception thrown
newNode.Red = true;
newNode.Parent.Red = false;
newNode.Parent.LeftChild.Red = true; //true
if (newNode.Parent.LeftChild.LeftChild != null)
{
newNode.Parent.LeftChild.LeftChild.Red = false;
}
}
else if (newNode == newNode.Parent.RightChild && newNode.Parent == newNode.Parent.Parent.LeftChild) //???????
{
RotateLeft(newNode.Parent);
RotateRight(newNode.Parent);
newNode.Red = false;
newNode.LeftChild.Red = true;
newNode.RightChild.Red = true;
if (newNode.RightChild.RightChild != null)
{
newNode.RightChild.RightChild.Red = false;
}
}
else
{
RotateRight(newNode.Parent);
RotateLeft(newNode.Parent);
newNode.Red = false;
newNode.RightChild.Red = true;
newNode.LeftChild.Red = true;
if (newNode.LeftChild.LeftChild != null)
{
newNode.LeftChild.LeftChild.Red = false;
}
}
}
}
_root.Red = false;
}
