public void Delete(T data)
{
lock (_synchRoot)
{
int localCount = _count;
if (_count > 0)
{
bool heightChanged = false;
//LinkedAvlTreeNode<T> newRoot;
bool elementDeleted = _root.DeleteElement(data, out _root, out heightChanged);
if (elementDeleted)
{
_count--;
}
}
}
}
internal bool DeleteElement(T data, out LinkedAvlTreeNode <T> node, out bool heightDecreased)
{
bool deletedLeft = true;
bool elementDeleted = false;
node = this;
int comparison = this.Data.CompareTo(data);
if (comparison > 0 && _left != null)
{
elementDeleted = _left.DeleteElement(data, out _left, out heightDecreased);
}
else if (comparison < 0 && _right != null)
{
elementDeleted = _right.DeleteElement(data, out _right, out heightDecreased);
deletedLeft = false;
}
else if (comparison == 0)
{
if (_left == null)
{
UnlinkThis();
node = _right; heightDecreased = true;
return(true);
}
else if (_right == null)
{
UnlinkThis();
node = _left; heightDecreased = true;
return(true);
}
else
{
SwapDataWithNextSmaller(this, this._left);
elementDeleted = _left.DeleteElement(data, out _left, out heightDecreased);
}
}
else
{
heightDecreased = false;
return(false);
}
if (heightDecreased && deletedLeft)
{
if (_balance == 0) // if an element is deleted on the left side, and the node was balanced the node is now taller on the right side
{ // but the overall height did not change
_balance = 1;
node = this;
heightDecreased = false;
}
else if (_balance > 0) // the right side was already taller; therefore we need to rearrange
{
if (_right._balance == 0) // the left subtree will be higher by one element
{
_right._balance = -1;
_balance = 1;
RotateRight(out node);
heightDecreased = false;
}
else if (_right._balance > 0) // the left subtree grows; therefore the overall size will shrink
{
_balance = 0;
_right._balance = 0;
RotateRight(out node);
heightDecreased = true;
}
else //(_right._balance < 0) // a double rotation is required
{
DoubleRotateRight(out node);
AdjustBalance(node);
heightDecreased = true;
}
}
else // the left subtree was higher; now left and right have the same hight
{
_balance = 0;
node = this;
heightDecreased = true;
}
}
else if (heightDecreased) // deleted right
{
if (_balance == 0) // if an element is deleted on the right side and the node was balanced, the node left subtree is now taller
{
_balance = -1;
node = this;
heightDecreased = false;
}
else if (_balance < 0) //the left subtree was taller; we need to rearrange
{
if (_left._balance == 0)
{
_left._balance = 1;
_balance = -1;
RotateLeft(out node);
heightDecreased = false;
}
else if (_left._balance < 0)
{
_balance = 0;
_left._balance = 0;
RotateLeft(out node);
heightDecreased = true;
}
else // left._balance > 0
{
DoubleRotateLeft(out node);
AdjustBalance(node);
heightDecreased = true;
}
}
else
{
_balance = 0;
node = this;
heightDecreased = true;
}
}
else // heigth of subtree did not change!
{
node = this;
heightDecreased = false;
}
return(elementDeleted);
}
