private static void FixSize(RandTreeNode <T> node)
{
if (node != null)
{
node.Size = GetSize(node.Left) + GetSize(node.Right) + 1;
}
}
public override void Remove(T item)
{
if (Contains(item))
{
Root = Remove(Root, item);
}
Count--;
}
private static RandTreeNode <T> InsertRoot(RandTreeNode <T> node, T item)
{
if (node == null)
{
return(new RandTreeNode <T>(item));
}
if (item.CompareTo(node.Item) > 0)
{
node.Left = InsertRoot(node.Left, item);
return(RotateRight(node));
}
node.Right = InsertRoot(node.Right, item);
return(RotateLeft(node));
}
private static RandTreeNode <T> TrySearch(RandTreeNode <T> node, T item)
{
while (true)
{
if (node == null)
{
return(null);
}
if (node.Item.CompareTo(item) == 0)
{
return(node);
}
node = item.CompareTo(node.Item) < 0 ? node.Left : node.Right;
}
}
private static RandTreeNode <T> RotateLeft(RandTreeNode <T> node)
{
var temp = node.Right;
if (temp == null || temp.Item.CompareTo(node.Item) == 0)
{
return(node);
}
node.Right = temp.Left;
temp.Left = node;
temp.Size = node.Size;
FixSize(node);
FixSize(temp);
return(temp);
}
private static RandTreeNode <T> Join(RandTreeNode <T> first, RandTreeNode <T> second)
{
if (first == null)
{
return(second);
}
if (second == null)
{
return(first);
}
if (_randomizer.Next(first.Size + second.Size) < first.Size)
{
first.Right = Join(first.Right, second);
FixSize(first);
return(first);
}
second.Left = Join(first, second.Left);
FixSize(second);
return(second);
}
private static RandTreeNode <T> Remove(RandTreeNode <T> node, T item)
{
if (node == null)
{
return(null);
}
if (node.Item.Equals(item))
{
return(Join(node.Left, node.Right));
}
if (node.Item.CompareTo(item) > 0)
{
node.Left = Remove(node.Left, item);
}
else
{
node.Right = Remove(node.Right, item);
}
FixSize(node);
return(node);
}
private static RandTreeNode <T> Insert(RandTreeNode <T> node, T item)
{
if (node == null)
{
return(new RandTreeNode <T>(item));
}
if (_randomizer.Next(node.Size + 1) == 0)
{
return(InsertRoot(node, item));
}
if (item.CompareTo(node.Item) > 0)
{
node.Left = Insert(node.Left, item);
}
else
{
node.Right = Insert(node.Right, item);
}
FixSize(node);
return(node);
}
public override void Insert(T item)
{
Root = Insert(Root, item);
Count++;
}
private static int GetSize(RandTreeNode <T> node) => node?.Size ?? 0;