/// <summary>
/// 1. Function that recursively displays the tree inorder from least to greatest.
/// </summary>
public void display(Node root)
{
if (root != null)
{
display(root.left);
Console.Write(root.data + " ");
display(root.right);
}
}
/// <summary>
/// Creates and returns a BST node
/// </summary>
public Node addNode(int data)
{
Node temp = new Node(data);
if (root == null)
{
root = temp;
}
count++;
return temp;
}
//get root
/// <summary>
/// Clear it all, clear it all!
/// </summary>
public void clear(Node root)
{
if (root == null)
{
return;
}
if (root.left != null)
{
clear(root.left);
}
if (root.right != null)
{
clear(root.right);
}
root = null;
return;
}
/// <summary>
/// Function that finds the max depth of the BST recursively
/// </summary>
public int getLevel(Node root)
{
if (root == null)
{
return 0;
}
else
{
int leftLevel = getLevel(root.left);
int rightLevel = getLevel(root.right);
if (rightLevel > leftLevel)
{
return (rightLevel + 1);
}
else
return (leftLevel + 1);
}
}
public BinarySearchTree()
{
root = null;
}
/// <summary>
/// Helper function (checks for duplicate node before adding) that recursively searches the BST given an int value.
/// Compares values to root first to save time.
/// </summary>
public bool search(Node root, int x)
{
if (root == null) // Case 1: Tree is empty
{
return false;
}
else if (root.data == x) // Case 2: Equal to root, duplicate found.
{
return true;
}
else if (root.data > x)
{ // Case 3: Less than root, recurse left
return search(root.left, x);
}
else // Case 4: Greater than root, recurse right
return search(root.right, x);
}
/// <summary>
/// 3. Function that doesn't use recursion nor stack to do an inorder traversal of the BST.
/// Apparently this algorithm is called the "Morris traversal" method. The resources I used to understand and implement it are cited in my references.
/// Although modifying the tree is necessary, it's reverted after traversal is done, as per the assignemtn requirements.
/// This algorithm, like Evan hinted, uses the null leaf nodes to determine when to stop and when to begin traversing left or right child nodes.
/// </summary>
public void In_Order_Traversal_3(Node root)
{
if (root != null)
{
Node current_node = root, prev_node = null;
while (current_node != null)
{
if (current_node.left == null) // Found furthest left, print
{
Console.Write(current_node.data);
Console.Write(" ");
current_node = current_node.right; // Next!
}
else
{
prev_node = current_node.left;
while (prev_node.right != current_node && prev_node.right != null)
{
prev_node = prev_node.right; // Find the previous node
}
if (prev_node.right == null)
{
prev_node.right = current_node; // Because prev_node.right can't be equal to current_node
current_node = current_node.left;
}
else // Revert the bst
{
Console.Write(current_node.data);
Console.Write(" ");
current_node = current_node.right; // Next!
prev_node.right = null;
}
}
}
}
else // Empty tree
{
return;
}
}
/// <summary>
/// 2. Non-recursive function that uses a stack to traverse the BST in order.
///
/// Algorithm/function given by Evan Olds in lecture 11/13:
///
/// public void In_Order_Traversal_2(Node root)
/// {
/// while (true)
/// {
/// stack<node> nodes = new Stack<node>();
///
/// while(n != null)
/// {
/// nodes.Push(n);
/// n=n.Left;
/// }
///
/// if (nodes.Count == 0){break;}
///
/// n = nodes.Pop()
/// console.write(n.Data.ToString() + " ");
/// n=n.right)
/// }
/// console.writeline();
/// }
/// </summary>
public void In_Order_Traversal_2(Node root)
{
Stack<Node> s = new Stack<Node>();
Node current_node = root; // Isn't necessary, we could just parameter root. Since it's only declared once, why not for
bool exit = false; // accurate variable names' sake.
if (root == null) // Check for empty tree
{
return;
}
while (s != null && !exit)
{
if (current_node != null)
{
s.Push(current_node);
current_node = current_node.left; // Lowest lefthand node
}
else
{
if (s.Count == 0)
{
exit = true;
}
else
{
current_node = s.Peek(); // Set the current node to the top element of stack w/o adjusting the stack. eg Pop() won't work
s.Pop();
Console.Write(current_node.data);
Console.Write(" ");
current_node = current_node.right;
}
}
}
}
/// <summary>
/// Inserts the new node in the right place
/// </summary>
public void insert(Node root, Node newNode)
{
while (root != null)
{
if (newNode.data > root.data)
{
if (root.right == null)
{
root.right = newNode;
break;
}
root = root.right;
}
else
{
if (root.left == null)
{
root.left = newNode;
break;
}
root = root.left;
}
}
}
public Node(int value)
{
data = value;
left = null;
right = null;
}
