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 tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.

For example, you may serialize the following tree

    1
   / \
  2   3
     / \
    4   5

as"[1,2,3,null,null,4,5]", just the same ashow LeetCode OJ serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.

Note:Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Codec {

    final String spliter = ",";
    final String NN = "#";

    // Encodes a tree to a single string.
    public String serialize(TreeNode root) {
        StringBuilder sb = new StringBuilder();
        buildString(root, sb);

        return sb.toString();
    }

    private void buildString(TreeNode root, StringBuilder sb){
        if (root == null){
            sb.append(NN).append(spliter);
        }
        else{
            sb.append(root.val + "").append(spliter);
            this.buildString(root.left, sb);
            this.buildString(root.right, sb);
        }
    }

    // Decodes your encoded data to tree.
    public TreeNode deserialize(String data) {
        Queue<String> q = new LinkedList<>();
        q.addAll(Arrays.asList(data.split(spliter)));

        return buildTree(q);
    }

    private TreeNode buildTree(Queue<String> q){
        String val = q.poll();
        if (val.equals(NN)) return null;

        TreeNode node = new TreeNode(Integer.valueOf(val));
        node.left = buildTree(q);
        node.right = buildTree(q);

        return node;
    }
}

// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));