public IList <int> Method(TreeNodePostorderTraversal root)
{
LinkedList <TreeNodePostorderTraversal> stack = new LinkedList <TreeNodePostorderTraversal>();
var list = new List <int>();
if (root == null)
{
return(list);
}
stack.AddLast(root);
while (stack.Count > 0)
{
TreeNodePostorderTraversal node = stack.Last();
stack.RemoveLast();
list.Insert(0, node.val);
if (node.left != null)
{
stack.AddLast(node.left);
}
if (node.right != null)
{
stack.AddLast(node.right);
}
}
return(list);
}
public TreeNodePostorderTraversal(int val = 0, TreeNodePostorderTraversal left = null, TreeNodePostorderTraversal right = null)
{
this.val = val;
this.left = left;
this.right = right;
}