LintCode-Serialization and Deserialization Of Binary Tree

 1 /**
 2  * Definition of TreeNode:
 3  * public class TreeNode {
 4  *     public int val;
 5  *     public TreeNode left, right;
 6  *     public TreeNode(int val) {
 7  *         this.val = val;
 8  *         this.left = this.right = null;
 9  *     }
10  * }
11  */
12 class Solution {
13     /**
14      * This method will be invoked first, you should design your own algorithm 
15      * to serialize a binary tree which denote by a root node to a string which
16      * can be easily deserialized by your own "deserialize" method later.
17      */
18     public String serialize(TreeNode root) {
19         String res = "";
20         if (root==null) return res;
21         
22         List<TreeNode> nodeList = new ArrayList<TreeNode>();
23         nodeList.add(root);
24         int index = 0;
25         res = Integer.toString(nodeList.get(0).val);
26         while (index<nodeList.size()){
27             TreeNode cur = nodeList.get(index);
28             if (cur==null){
29                 res += ",#,#";
30             } else {
31                 if (cur.left!=null){
32                     nodeList.add(cur.left);
33                     res += ","+cur.left.val;
34                 } else res += ",#";
35                 if (cur.right!=null){
36                     nodeList.add(cur.right);
37                     res += ","+cur.right.val;
38                 } else res += ",#";
39             }
40             index++;
41         }       
42         
43         return res;
44     }
45     
46     /**
47      * This method will be invoked second, the argument data is what exactly
48      * you serialized at method "serialize", that means the data is not given by
49      * system, it‘s given by your own serialize method. So the format of data is
50      * designed by yourself, and deserialize it here as you serialize it in 
51      * "serialize" method.
52      */
53     public TreeNode deserialize(String data) {
54         if (data.isEmpty()) return null;
55         String[] temp = data.split(",");
56         TreeNode root = new TreeNode(Integer.parseInt(temp[0]));
57         List<TreeNode> nodeList = new ArrayList<TreeNode>();
58         nodeList.add(root);
59         int cur = 0, next = 1;
60         while (cur<nodeList.size()){
61             TreeNode curNode = nodeList.get(cur);
62             if (curNode==null) cur++;
63             else {           
64                 int left = next;
65                 int right = next+1;
66                 if (next<temp.length){
67                     if (temp[next].equals("#")) nodeList.add(null);
68                     else {
69                         TreeNode leftChild = new TreeNode(Integer.parseInt(temp[next]));
70                         curNode.left = leftChild;
71                         nodeList.add(leftChild);
72                     }
73                 }
74                 if (next+1<temp.length){
75                     if (temp[next+1].equals("#")) nodeList.add(null);
76                     else {
77                         TreeNode rightChild = new TreeNode(Integer.parseInt(temp[next+1]));
78                         curNode.right = rightChild;
79                         nodeList.add(rightChild);
80                     }
81                 }
82                 next += 2;
83                 cur++;
84             }
85         }
86         
87         
88         
89         return root;    
90     }
91 }