Update SerializeDeserializeBST.java

Author: techieJarek

SerializeDeserializeBST.java

@@ -1,5 +1,19 @@
 import java.util.*;
 
+/** 
+Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored
+ in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or 
+ another computer environment.
+
+Design an algorithm to serialize and deserialize a binary search tree. There is no restriction on how your 
+serialization/deserialization algorithm should work. You just need to ensure that a binary search tree can be serialized 
+to a string and this string can be deserialized to the original tree structure.
+
+The encoded string should be as compact as possible.
+
+Note: Do not use class member/global/static variables to store states. 
+Your serialize and deserialize algorithms should be stateless.
+ */
 public class SerializeDeserializeBST {
     public static class TreeNode {
         int val;
@@ -28,6 +42,7 @@ public static void main(String args[]){
     }
 
     private static String serialize(TreeNode root) {
+        if(root == null) return null;
         Queue<Integer> q = new LinkedList<>();
         serialize(root, q);
         String result = "";
@@ -45,6 +60,7 @@ private static void serialize(TreeNode root, Queue<Integer> q) {
     }
 
     private static TreeNode deserialize(String serialized) {
+        if(serialized == null) return null;
         String[] array = serialized.split("#");
         Queue<Integer> q = new LinkedList<>();