/// <summary> /// Removes all items from the tree /// </summary> public void Clear() { _head = null; _count = 0; }
/// <summary> /// Removes the first occurance 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) { BinaryTreeNode <T> current, parent; current = FindWithParent(value, out parent); if (current == null) { return(false); } _count--; // Case 1: If current has no right child, then current's left replaces current if (current.Right == null) { if (parent == null) { _head = current.Left; } else { int result = parent.CompareTo(current.Value); if (result > 0) { // if parent value is greater than current value // make the current left child a left child of parent parent.Left = current.Left; } else if (result < 0) { // if parent value is less than current value // make the current left child a right child of parent 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 (parent == null) { _head = current.Right; } else { int result = parent.CompareTo(current.Value); if (result > 0) { // if parent value is greater than current value // make the current right child a left child of parent parent.Left = current.Right; } else if (result < 0) { // if parent value is less than current value // make the current right child a right child of parent parent.Right = current.Right; } } } // Case 3: If current's right child has a left child, replace current with current's // right child's left-most child else { // find the right's left-most child BinaryTreeNode <T> leftmost = current.Right.Left; BinaryTreeNode <T> leftmostParent = current.Right; while (leftmost.Left != null) { leftmostParent = leftmost; leftmost = leftmost.Left; } // the parent's left subtree becomes the leftmost's right subtree leftmostParent.Left = leftmost.Right; // assign leftmost's left and right to current's left and right children leftmost.Left = current.Left; leftmost.Right = current.Right; if (parent == null) { _head = leftmost; } else { int result = parent.CompareTo(current.Value); if (result > 0) { // if parent value is greater than current value // make leftmost the parent's left child parent.Left = leftmost; } else if (result < 0) { // if parent value is less than current value // make leftmost the parent's right child parent.Right = leftmost; } } } return(true); }