private void BalanceAfterRemoving(AVLNode <TKey, TValue> node, int balance)
{
while (node != null)
{
node.Balance += balance;
balance = node.Balance;
if (balance == 2)
{
if (node.Left.Balance >= 0)
{
node = RotateRight(node);
if (node.Balance == -1)
{
return;
}
}
else
{
node = RotateLeftRight(node);
}
}
else if (balance == -2)
{
if (node.Right.Balance <= 0)
{
node = RotateLeft(node);
if (node.Balance == 1)
{
return;
}
}
else
{
node = RotateRightLeft(node);
}
}
else if (balance != 0)
{
return;
}
var parent = node.Parent;
if (parent != null)
{
if (parent.Left == node)
{
balance = -1;
}
else
{
balance = 1;
}
}
node = parent;
}
}
public void Clear()
{
_root = null;
Count = 0;
}
public bool Remove(TKey key)
{
var node = _root;
while (node != null)
{
if (key.CompareTo(node.Key) < 0)
{
node = node.Left;
}
else if (key.CompareTo(node.Key) > 0)
{
node = node.Right;
}
else
{
var left = node.Left;
var right = node.Right;
if (left == null)
{
if (right == null)
{
if (node == _root)
{
_root = null;
}
else
{
var parent = node.Parent;
if (parent.Left == node)
{
parent.Left = null;
BalanceAfterRemoving(parent, -1);
}
else
{
parent.Right = null;
BalanceAfterRemoving(parent, 1);
}
}
}
else
{
Replace(node, right);
BalanceAfterRemoving(node, 0);
}
}
else if (right == null)
{
Replace(node, left);
BalanceAfterRemoving(node, 0);
}
else
{
var next = right;
if (next.Left == null)
{
var parent = node.Parent;
next.Parent = parent;
next.Left = left;
next.Balance = node.Balance;
left.Parent = next;
if (node == _root)
{
_root = next;
}
else
{
if (parent.Left == node)
{
parent.Left = next;
}
else
{
parent.Right = next;
}
}
BalanceAfterRemoving(next, 1);
}
else
{
while (next.Left != null)
{
next = next.Left;
}
var parent = node.Parent;
var nextParent = next.Parent;
var nextRight = next.Right;
if (nextParent.Left == next)
{
nextParent.Left = nextRight;
}
else
{
nextParent.Right = nextRight;
}
if (nextRight != null)
{
nextRight.Parent = nextParent;
}
next.Parent = parent;
next.Left = left;
next.Balance = node.Balance;
next.Right = right;
right.Parent = next;
left.Parent = next;
if (node == _root)
{
_root = next;
}
else
{
if (parent.Left == node)
{
parent.Left = next;
}
else
{
parent.Right = next;
}
}
BalanceAfterRemoving(nextParent, -1);
}
}
Count--;
return(true);
}
}
return(false);
}
