Serialize and Deserialize Binary Tree

 1 /**
 2  * Definition for a binary tree node.
 3  * public class TreeNode {
 4  *     int val;
 5  *     TreeNode left;
 6  *     TreeNode right;
 7  *     TreeNode(int x) { val = x; }
 8  * }
 9  */
10 import java.util.*;
11 public class Codec {
12 
13     // Encodes a tree to a single string.
14     public String serialize(TreeNode root) {
15         if (root == null) {
16             return null;
17         }
18         StringBuilder result = new StringBuilder();
19         serl(root, result);
20         return result.toString();
21     }
22     
23     private void serl(TreeNode root, StringBuilder result) {
24         if (root == null) {
25             result.append("# ");
26             return;
27         }
28         result.append(root.val + " ");
29         serl(root.left, result);
30         serl(root.right, result);
31     }
32 
33     // Decodes your encoded data to tree.
34     public TreeNode deserialize(String data) {
35         if (data == null) {
36             return null;
37         }
38         StringTokenizer st = new StringTokenizer(data, " ");
39         return derl(st);
40     }
41     private TreeNode derl(StringTokenizer st) {
42         if (st == null) {
43             return null;
44         }    
45     
46         if (!st.hasMoreTokens()) {
47             return null;
48         }
49         String current = st.nextToken();
50         if (current.equals("#")) {
51             return null;
52         }
53         
54         TreeNode root = new TreeNode(Integer.parseInt(current));
55         root.left = derl(st);
56         root.right = derl(st);
57         return root;
58     }
59 }
60 
61 // Your Codec object will be instantiated and called as such:
62 // Codec codec = new Codec();
63 // codec.deserialize(codec.serialize(root));
posted on 2016-07-06 07:33 keepshuatishuati 阅读(139) 评论(0) 编辑收藏举报