@@ -151,6 +151,7 @@ public TreeNode deserialize(String data) {
151151return root ;
152152 }
153153 }
154+
154155public static class Solution4 {
155156private static final String NULL_SYMBOL ="X" ;
156157private static final String DELIMITER ="," ;
@@ -159,8 +160,9 @@ public static class Solution4 {
159160public String serialize (TreeNode root ) {
160161
161162// If we have a null symbol, encode it to NULL_SYMBOL
162- if (root ==null )
163+ if root ==null ) {
163164return NULL_SYMBOL +DELIMITER ;
165+ }
164166
165167String leftSubtree =serialize (root .left );
166168String rightSubtree =serialize (root .right );
@@ -176,12 +178,13 @@ public TreeNode deserialize(String data) {
176178return deserializeHelper (nodesLeftToSerialize );
177179
178180 }
179- private TreeNode deserializeHelper (Queue <String >nodesLeft ){
181+
182+ private TreeNode deserializeHelper (Queue <String >nodesLeft ) {
180183
181184// remove the node
182185String nodeLeftToSerialize =nodesLeft .poll ();
183186// base case
184- if (nodeLeftToSerialize .equals (NULL_SYMBOL )){
187+ if nodeLeftToSerialize .equals (NULL_SYMBOL ))
185188return null ;
186189 }
187190TreeNode newNode =new TreeNode (Integer .valueOf (nodeLeftToSerialize ));