// Function that adds the movie object into the BST.
public void Insert(Movie movie)
{
// Setup a new TreeNode to add to BST.
TreeNode newTreeNode = new TreeNode();
// Assign the movie object to the movie object in the TreeNode.
newTreeNode.movie = movie;
bool exit = false;
// If there is no root in the BST, set the root to the new tree
// node.
// Increment the count of movies in the tree.
if (root == null)
{
root = newTreeNode;
movieCount++;
}
else
{
// Setup a new treeNode for the current node and parent node
// to start comparisons when travelling in tree.
TreeNode current = root;
TreeNode parent;
while (!exit)
{
// Assign parent node to the current node being compared.
parent = current;
// If the comparison returns -1, traverse left side of
// current node.
if (string.Compare
(movie.GetTitle(), current.movie.GetTitle()) == -1)
{
// Assign the left node of the current node to the
// current variable
current = current.left;
//If its empty add at this location
if (current == null)
{
// Add treeNode to parent of current.
parent.left = newTreeNode;
// Increase count of movies in BST.
movieCount++;
exit = true;
}
}
else
{
//Assign the right node of the current node to the
// current variable
current = current.right;
//If its empty add at this location
if (current == null)
{
// Add treeNode to parent of current.
parent.right = newTreeNode;
// Increase count of movies in BST.
movieCount++;
exit = true;
}
}
}
}
}
// Function that deletes the movie from the BST - accounts for 0
// children, 1 child on L or R and 2 children deletion.
// No output.
public bool Delete(Movie movie, MemberCollection memberCollection)
{
// Check to see if the movie is already rented to a user.
Movie[] rentedMovies =
memberCollection.ReturnCurrentBorrowedMovies();
bool check = false;
// Mark check as true if the entered movie is currently rented.
foreach (Movie m in rentedMovies)
{
if (m.GetTitle() == movie.GetTitle())
{
check = true;
}
}
//If it is not currently rented out to user, delete the movie
// from BST.
if (!check)
{
TreeNode current = root;
TreeNode parent = root;
bool leftNode = true;
// Check to see if the current movie is the user entered
// movie then traverse the BST based off name comparison.
while (current.movie.GetTitle() != movie.GetTitle())
{
parent = current;
// If searched name is less than current node, travel
// left tree.
if (string.Compare(movie.GetTitle(),
current.movie.GetTitle()) == -1)
{
leftNode = true;
current = current.left;
}
// If searched name is greater than current node, travel
// right tree.
else
{
leftNode = false;
current = current.right;
}
if (current == null)
{
return(false);
}
}
if ((current.left == null) && (current.right == null))
{
// Delete the node as it has no children.
if (current == root)
{
root = null;
return(true);
}
// Delete the left child
else if (leftNode)
{
parent.left = null;
return(true);
}
// Delete the right child
else
{
parent.right = null;
return(true);
}
}
// If current node's right node is empty, replace with left
// node
else if (current.right == null)
{
if (current == root)
{
root = current.left;
return(true);
}
// Replace current node with its left child in BST.
else if (leftNode)
{
parent.left = current.left;
return(true);
}
// Replace current node with its right child in BST.
else
{
parent.right = current.left;
return(true);
}
}
// If current node's left node is empty, replace with right
// node
else if (current.left == null)
{
if (current == root)
{
root = current.right;
return(true);
}
// Replace current node with its left child in BST.
else if (leftNode)
{
parent.left = current.right;
return(true);
}
// Replace current node with its right child in BST.
else
{
parent.right = current.right;
return(true);
}
}
// Node has 2 children
else
{
// If far right most node of current node is empty,
// current node becomes left node.
if (current.left.right == null)
{
current.movie = current.left.movie;
current.left = current.left.left;
return(true);
}
// Replace current node with the far right most node.
else
{
TreeNode node = current.left;
TreeNode parentNode = current;
while (node.right != null)
{
parentNode = node;
node = node.right;
}
current.movie = node.movie;
parentNode.right = node.left;
return(true);
}
}
}
else
{
Console.WriteLine("You cannot delete a " +
"movie that is currently rented out.");
return(false);
}
}
