/// <summary>
/// private helper method: Calculate the subtree height
/// this method takes the direct child's height property and return the maximum height
/// </summary>
/// <param name="node"> the node needs to get its subtree height </param>
/// <returns> returns the height of the subtree</returns>
private int GetSubtreeHeight(AvlNode <T> node)
{
if (node.IsLeafNode())
{
return(0); //no nodes below, height is 0 below
}
//two child, return the maximum height between left and right subtree.
if (!node.HasOneChild())
{
return(Math.Max(node.Left.Height, node.Right.Height));
}
//Only one child, return that child's height
return(node.Left?.Height ?? node.Right.Height);
}
/// <summary>
/// private helper method: calculate the balancing factor of given node
/// </summary>
/// <param name="node"> node need to calculate balancing factor</param>
/// <returns></returns>
private int GetBalancingFactor(AvlNode <T> node)
{
//no child, balancing factor is 0
if (node.IsLeafNode())
{
return(0);
}
//has two child, balancing factor is height of left subtree - height of right subtree
if (!node.HasOneChild())
{
return(node.Left.Height - node.Right.Height);
}
//only one child, return that child's height
if (node.Left != null) //child on the left
{
return(node.Left.Height);
}
return(0 - node.Right.Height); //child on the right
}