private void SetBalanceAfterDoubleRotation(AVLElement subRoot)
{
var right = (AVLElement)subRoot.ChildRight;
var left = (AVLElement)subRoot.ChildLeft;
switch (subRoot.BalanceFactor)
{
case -1:
left.BalanceFactor = 0;
right.BalanceFactor = 1;
break;
case 1:
left.BalanceFactor = -1;
right.BalanceFactor = 0;
break;
case 0:
left.BalanceFactor = right.BalanceFactor = 0;
break;
}
subRoot.BalanceFactor = 0;
}
public override bool Insert(int elem)
{
if (this.Search(elem))
{
return(false);
}
AVLElement add = new AVLElement(elem);
if (RootElement == null)
{
this.RootElement = add;
}
else if (elem < current.Value)
{
current.ChildLeft = add;
AddedLeft(current as AVLElement);
}
else
{
current.ChildRight = add;
AddedRight(current as AVLElement);
}
return(true);
}
private void AddedLeft(AVLElement element)
{
element.BalanceFactor--;
switch (element.BalanceFactor)
{
case 0:
return;
case -1:
if (element == RootElement)
{
return;
}
if (element.Parent.ChildRight == element)
{
AddedRight(element.Parent as AVLElement);
}
else
{
AddedLeft(element.Parent as AVLElement);
}
break;
case -2:
if ((element.ChildLeft as AVLElement).BalanceFactor == 1)
{
RotateLeft(element.ChildLeft.ChildRight);
RotateRight(element.ChildLeft);
SetBalanceAfterDoubleRotation(element.Parent as AVLElement);
}
else
{
RotateRight(element.ChildLeft);
element.BalanceFactor = 0;
(element.Parent as AVLElement).BalanceFactor = 0;
}
break;
}
}
private void RemovedRight(AVLElement element)
{
element.BalanceFactor--;
switch (element.BalanceFactor)
{
case -1:
return;
case 0:
if (element == RootElement)
{
return;
}
if (element.Parent.ChildRight == element)
{
RemovedRight(element.Parent as AVLElement);
}
else
{
RemovedLeft(element.Parent as AVLElement);
}
break;
case -2:
AVLElement subRoot;
if ((element.ChildLeft as AVLElement).BalanceFactor == 1)
{
RotateLeft(element.ChildLeft.ChildRight);
RotateRight(element.ChildLeft);
subRoot = element.Parent as AVLElement;
SetBalanceAfterDoubleRotation(subRoot);
}
else
{
RotateRight(element.ChildLeft);
subRoot = element.Parent as AVLElement;
if (subRoot.BalanceFactor == 0)
{
subRoot.BalanceFactor = 1;
element.BalanceFactor = -1;
return;
}
element.BalanceFactor = subRoot.BalanceFactor = 0;
}
if (subRoot == RootElement)
{
return;
}
if (subRoot.Parent.ChildRight == subRoot)
{
RemovedRight(subRoot.Parent as AVLElement);
}
else
{
RemovedLeft(subRoot.Parent as AVLElement);
}
break;
}
}