Method tree

java/0872-leaf-similar-trees.java:9–16

(TreeNode root, List<Integer> ls)

        return ls1.equals(ls2);
    }
    private void tree(TreeNode root, List<Integer> ls){
        if(root == null)
            return;
        if(root.left == null && root.right == null)
            ls.add(root.val);
        tree(root.left, ls);
        tree(root.right, ls);        
    }
}