Leetcode 297. Serialize and Deserialize Binary Tree (Hard) (cpp)

Leetcode 297. Serialize and Deserialize Binary Tree (Hard) (cpp)

Tag: Design, Tree

Difficulty: Hard

/*

297. Serialize and Deserialize Binary Tree (Hard)

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 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.

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

	// Encodes a tree to a single string.
	string serialize(TreeNode* root) {
		ostringstream out;
		serialize(root, out);
		return out.str();
	}

	// Decodes your encoded data to tree.
	TreeNode* deserialize(string data) {
		istringstream in(data);
		return deserialize(in);
	}
private:
	void serialize(TreeNode* root, ostringstream& out) {
		if (root) {
			out << root->val << ' ';
			serialize(root->left, out);
			serialize(root->right, out);
		}
		else {
			out << "# ";
		}
	}
	TreeNode* deserialize(istringstream& in) {
		string val;
		in >> val;
		if (val == "#")
			return nullptr;
		TreeNode* root = new TreeNode(stoi(val));
		root->left = deserialize(in);
		root->right = deserialize(in);
		return root;
	}
};
// Your Codec object will be instantiated and called as such:
// Codec codec;
// codec.deserialize(codec.serialize(root));