예제 #1
0
 public AVLTreeNode(TNode value, AVLTreeNode <TNode> parent, AVLTree <TNode> tree)
 {
     Value  = value;
     Parent = parent;
     _tree  = tree;
 }
예제 #2
0
        /// <summary>
        /// Removes the first occurrence of the specified value from the tree.
        /// </summary>
        /// <param name="value">The value to remove.</param>
        /// <returns>True if the value was removed; false otherwise.</returns>
        public bool Remove(T value) // O(log n)
        {
            AVLTreeNode <T> current;

            current = Find(value);
            if (current == null)
            {
                return(false);
            }

            AVLTreeNode <T> treeToBalance = current.Parent;

            Count--;

            //Case 1: If current has no right child, then current's left replaces current.
            if (current.Right == null)
            {
                if (current.Parent == null)
                {
                    Head = current.Left;
                    if (Head != null)
                    {
                        Head.Parent = null;
                    }
                }
                else
                {
                    int result = current.Parent.CompareTo(current.Value);
                    if (result > 0)
                    {
                        // If the parent value is greater than the current value,
                        // make the current left child a left child of parent.
                        current.Parent.Left = current.Left;
                    }
                    else if (result < 0)
                    {
                        // If the parent value is less than the current value,
                        // make the current left child a right child of the parent.
                        current.Parent.Right = current.Left;
                    }
                }
            }
            // Case 2: If current's right child has no left child, then current's right child replaces current.
            else if (current.Right.Left == null)
            {
                current.Right.Left = current.Left;
                if (current.Parent == null)
                {
                    Head = current.Right;
                    if (Head != null)
                    {
                        Head.Parent = null;
                    }
                }
                else
                {
                    int result = current.Parent.CompareTo(current.Value);
                    if (result > 0)
                    {
                        // If the parent value is greater than the current value,
                        // make the current the right child a left child of parent.
                        current.Parent.Left = current.Right;
                    }
                }
            }
            // Case 3: If current's right child has a left child, replace current with
            // current's right child's leftmost child.
            else
            {
                // Find the right's leftmost child.
                AVLTreeNode <T> leftmost = current.Right.Left;
                while (leftmost.Left != null)
                {
                    leftmost = leftmost.Left;
                }
                // The parent's left subtree becomes the leftmost's right subtree.
                leftmost.Parent.Left = leftmost.Right;
                //Asign leftmost's left and right to current's left and right children.
                leftmost.Left  = current.Left;
                leftmost.Right = current.Right;
                if (current.Parent == null)
                {
                    Head = leftmost;
                    if (Head != null)
                    {
                        Head.Parent = null;
                    }
                }
                else
                {
                    int result = current.Parent.CompareTo(current.Value);
                    if (result > 0)
                    {
                        // If the parent value is greater than the current value,
                        // make leftmost the parent's left child.
                        current.Parent.Left = leftmost;
                    }
                    else if (result < 0)
                    {
                        // If the parent value is less than the current value,
                        // make the leftmost parent's right child.
                        current.Parent.Right = leftmost;
                    }
                }
            }
            if (treeToBalance != null)
            {
                treeToBalance.Balance();
            }
            else
            {
                if (Head != null)
                {
                    Head.Balance();
                }
            }
            return(true);
        }
예제 #3
0
 public void Clear() // O(1)
 {
     Head  = null;
     Count = 0;
 }