//reorder the tree node so that heap property is valid
private void heapify(TreapTreeNode <T> node)
{
while (node.Parent != null)
{
node.UpdateCounts();
if (node.Priority < node.Parent.Priority)
{
node = node.IsLeftChild ? rightRotate(node.Parent) : leftRotate(node.Parent);
}
else
{
break;
}
}
node.UpdateCounts(true);
}
private void delete(TreapTreeNode <T> node, T value)
{
while (true)
{
if (node != null)
{
var compareResult = comparer.Compare(node.Value, value);
//node is less than the search value so move right to find the deletion node
if (compareResult < 0)
{
node = node.Right ?? throw new Exception("Item do not exist");
continue;
}
//node is less than the search value so move left to find the deletion node
if (compareResult > 0)
{
node = node.Left ?? throw new Exception("Item do not exist");
continue;
}
}
//node is a leaf node
if (node != null && node.IsLeaf)
{
deleteLeaf(node);
}
else
{
//case one - right tree is null (move sub tree up)
if (node?.Left != null && node.Right == null)
{
deleteLeftNode(node);
}
//case two - left tree is null (move sub tree up)
else if (node?.Right != null && node.Left == null)
{
deleteRightNode(node);
}
//case three - two child trees
//replace the node value with maximum element of left subtree (left max node)
//and then delete the left max node
else
{
if (node != null)
{
var maxLeftNode = findMax(node.Left);
node.Value = maxLeftNode.Value;
//delete left max node
node = node.Left;
value = maxLeftNode.Value;
}
continue;
}
}
break;
}
node.UpdateCounts(true);
}