private AvlNode Delete(AvlNode tree, string key)
{
if (tree == null)
{
return(null);
}
if (string.Compare(key, tree.Key) > 0)
{
tree.Right = Delete(tree.Right, key);
}
else if (string.Compare(key, tree.Key) < 0)
{
tree.Left = Delete(tree.Left, key);
}
else
{
if (tree.Left == null && tree.Right == null)
{
return(null);
}
else if (tree.Left == null && tree.Right != null)
{
return(tree.Right);
}
else if (tree.Left != null && tree.Right == null)
{
return(tree.Left);
}
else
{
AvlNode temp = MaxValueNode(tree.Left);
tree.Key = temp.Key;
tree.Value = temp.Value;
tree.Left = Delete(tree.Left, temp.Key);
}
}
return(Balance(tree));
}
static AvlNode CloneNode(AvlNode node)
{
if (node == null)
{
return(null);
}
var ret = new AvlNode
{
Left = node.Left,
Right = node.Right,
Parent = node.Parent,
Value = node.Value,
Height = node.Height
};
return(ret);
}
private bool Contains(AvlNode tree, string key, ref int value)
{
if (tree == null)
{
return(false);
}
else if (string.Compare(key, tree.Key) > 0)
{
return(Contains(tree.Right, key, ref value));
}
else if (string.Compare(key, tree.Key) < 0)
{
return(Contains(tree.Left, key, ref value));
}
else
{
value = tree.Value;
return(true);
}
}
private AvlNode Insert(AvlNode tree, string key, int value)
{
if (tree == null)
{
return new AvlNode {
Key = key, Value = value
}
}
;
else if (string.Compare(key, tree.Key) > 0)
{
tree.Right = Insert(tree.Right, key, value);
}
else if (string.Compare(key, tree.Key) < 0)
{
tree.Left = Insert(tree.Left, key, value);
}
return(Balance(tree));
}
static void Add(AvlNode node, int value, AvlNode parent = null)
{
var newNode = new AvlNode
{
Left = null,
Right = null,
Value = value,
Parent = node
};
if (value >= node.Value)
{
if (node.Right == null)
{
node.Right = newNode;
MaintainHeightAfterInsert(newNode);
Modify(newNode);
}
else
{
Add(node.Right, value, node);
}
}
else
{
if (node.Left == null)
{
node.Left = newNode;
MaintainHeightAfterInsert(newNode);
Modify(newNode);
}
else
{
Add(node.Left, value, node);
}
}
}
private AvlNode Balance(AvlNode tree)
{
FixHeight(tree);
if (BalanceFactor(tree) == 2)
{
if (BalanceFactor(tree.Right) < 0)
{
tree.Right = RotateRight(tree.Right);
}
return(RotateLeft(tree));
}
if (BalanceFactor(tree) == -2)
{
if (BalanceFactor(tree.Left) > 0)
{
tree.Left = RotateLeft(tree.Left);
}
return(RotateRight(tree));
}
return(tree);
}
public void Clear()
{
MakeEmpty(_root);
_root = null;
}
public void Remove(string key)
{
_root = Delete(_root, key);
}
public void Add(string key, int value)
{
_root = Insert(_root, key, value);
}
private int BalanceFactor(AvlNode tree)
{
return(Height(tree.Right) - Height(tree.Left));
}
private void FixHeight(AvlNode tree)
{
tree.Height = Math.Max(Height(tree.Left), Height(tree.Right)) + 1;
}
private int Height(AvlNode tree)
{
return(tree == null ? -1 : tree.Height);
}
