public static IList<IList<int>> LevelOrderBottom(TreeNode root)
{
if(root == null) return new List<IList<int>>();
List<IList<int>> result = new List<IList<int>>();
List<int> level = new List<int>();
var queue = new Queue<NodeWithHeight>();
int height = 0;
var temp = new NodeWithHeight(root,height);
queue.Enqueue(temp);
while(queue.Count != 0){
temp = queue.Dequeue();
if (temp.Height > height)
{
result.Insert(0, level);
height = temp.Height;
level = new List<int>();
level.Add(temp.Node.val);
}
else
level.Add(temp.Node.val);
if (temp.Node.left != null)
queue.Enqueue(new NodeWithHeight(temp.Node.left, temp.Height + 1));
if (temp.Node.right != null)
queue.Enqueue(new NodeWithHeight(temp.Node.right, temp.Height + 1));
}
if (level.Count != 0)
result.Insert(0, level);
return result;
}
public static IList <IList <int> > LevelOrderBottom(TreeNode root)
{
if (root == null)
{
return(new List <IList <int> >());
}
List <IList <int> > result = new List <IList <int> >();
List <int> level = new List <int>();
var queue = new Queue <NodeWithHeight>();
int height = 0;
var temp = new NodeWithHeight(root, height);
queue.Enqueue(temp);
while (queue.Count != 0)
{
temp = queue.Dequeue();
if (temp.Height > height)
{
result.Insert(0, level);
height = temp.Height;
level = new List <int>();
level.Add(temp.Node.val);
}
else
{
level.Add(temp.Node.val);
}
if (temp.Node.left != null)
{
queue.Enqueue(new NodeWithHeight(temp.Node.left, temp.Height + 1));
}
if (temp.Node.right != null)
{
queue.Enqueue(new NodeWithHeight(temp.Node.right, temp.Height + 1));
}
}
if (level.Count != 0)
{
result.Insert(0, level);
}
return(result);
}