private static void IsBalancedImpl(TreeNode <T> node, SortedSet <int> leafDepths, int currentDepth)
{
currentDepth++;
if (node.Left != null && node.Right != null)
{
leafDepths.Append(currentDepth);
}
if (node.Left != null)
{
IsBalancedImpl(node.Left, leafDepths, currentDepth);
}
else if (node.Right != null)
{
IsBalancedImpl(node.Right, leafDepths, currentDepth);
}
}
