private static void Helper(LeetCode103TreeNode root, int level)
{
if (root == null)
{
return;
}
if (level >= ans.Count)
{
var temp = new List <int>();
temp.Add(root.val);
ans.Add(temp);
}
else
{
if (level % 2 == 0)
{
ans[level].Add(root.val);
}
else
{
ans[level].Insert(0, root.val);
}
}
if (root.left != null)
{
Helper(root.left, level + 1);
}
if (root.right != null)
{
Helper(root.right, level + 1);
}
}
public static IList <IList <int> > ZigzagLevelOrder(LeetCode103TreeNode root)
{
Helper(root, 0);
return(ans);
}
public LeetCode103TreeNode(int val = 0, LeetCode103TreeNode left = null, LeetCode103TreeNode right = null)
{
this.val = val;
this.left = left;
this.right = right;
}