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 5as
"[1,2,3,null,null,4,5]"
, just the same as how 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.
[Thoughts]
这题纯粹是一道实现题,没有难点。看Code。
[Code]
1: /**
2: * Definition for a binary tree node.
3: * struct TreeNode {
4: * int val;
5: * TreeNode *left;
6: * TreeNode *right;
7: * TreeNode(int x) : val(x), left(NULL), right(NULL) {}
8: * };
9: */
10: class Codec {
11: public:
12:
13: // Encodes a tree to a single string.
14: string serialize(TreeNode* root) {
15: stringstream ss;
16: serializeImpl(root, ss);
17: return ss.str();
18: }
19:
20: // Decodes your encoded data to tree.
21: TreeNode* deserialize(string data) {
22: std::istringstream ss(data);
23: return deserializeImpl(ss);
24: }
25:
26: void serializeImpl(TreeNode* root, stringstream& ss) {
27: if(root == NULL) {
28: ss<<"#,";
29: return;
30: }
31:
32: ss << root->val << ",";
33: serializeImpl(root->left, ss);
34: serializeImpl(root->right, ss);
35: }
36:
37: TreeNode* deserializeImpl(istringstream & ss) {
38: std::string token;
39:
40: std::getline(ss, token, ',');
41:
42: if(token == "#") {
43: return NULL;
44: }
45:
46: TreeNode* root = new TreeNode(stoi(token));
47:
48: root->left = deserializeImpl(ss);
49: root->right = deserializeImpl(ss);
50: return root;
51: }
52:
53:
54: };
55:
56: // Your Codec object will be instantiated and called as such:
57: // Codec codec;
58: // codec.deserialize(codec.serialize(root));
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