tree level order reverse

src/com/dsa/trees/LevelOrderTraversal.java

@@ -28,7 +28,7 @@ public class LevelOrderTraversal {
                 }
                 index++;
             }
-            List<List<Integer>> list = levelOrder(root);
+            List<List<Integer>> list = levelOrderBottom(root);
             for (List<Integer> level : list) {
                 System.out.println(level);
             }
@@ -55,4 +55,23 @@ public class LevelOrderTraversal {
         }
         return res;
     }
+
+    public static List<List<Integer>> levelOrderBottom(TreeNode root) {
+        List<List<Integer>> res = new LinkedList<>();
+        if (root == null) return res;
+        Queue<TreeNode> queue = new LinkedList<>();
+        queue.offer(root);
+        while (!queue.isEmpty()) {
+            List<Integer> list = new LinkedList<>();
+            int size = queue.size();
+            for (int i = 0; i < size; i++) {
+                TreeNode node = queue.poll();
+                list.add(node.val);
+                if (node.left != null) queue.offer(node.left);
+                if (node.right != null) queue.offer(node.right);
+            }
+            res.addFirst(list);
+        }
+        return res;
+    }
 }