二叉树 序列化 反序列化

public class Solution {
    public int index = -1;
 3     StringBuilder s = new StringBuilder();
    String Serialize(TreeNode root) { 
 5         if(root == null){
            s.append("#,");
            return s.toString();
        }
        s.append(root.val+",");
        s.append(Serialize(root.left));
        s.append(Serialize(root.right));
        return s.toString();
    }
    TreeNode Deserialize(String str) {
        index++;
        String[] DLRseq = str.split(",");
        TreeNode leave = null;
        if(!DLRseq[index].equals("#")){
            leave = new TreeNode(Integer.valueOf(DLRseq[index]));
            leave.left = Deserialize(str);
            leave.right = Deserialize(str);
        }
        return leave;
    }  
}