297. Serialize and Deserialize Binary Tree
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.
Clarification: The input/output format is the same as how LeetCode serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.
Example 1:
Input: root = [1,2,3,null,null,4,5]
Output: [1,2,3,null,null,4,5]
Example 2:
Input: root = []
Output: []
Example 3:
Input: root = [1]
Output: [1]
Example 4:
Input: root = [1,2]
Output: [1,2]
Constraints:
- The number of nodes in the tree is in the range [0, 104].
- -1000 <= Node.val <= 1000
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Codec {
public String serialize(TreeNode root) {
return serial(new StringBuilder(), root).toString();
}
// Generate preorder string
private StringBuilder serial(StringBuilder str, TreeNode root) {
if (root == null) return str.append("#");
str.append(root.val).append(",");
serial(str, root.left).append(",");
serial(str, root.right);
return str;
}
public TreeNode deserialize(String data) {
return deserial(new LinkedList<>(Arrays.asList(data.split(","))));
}
// Use queue to simplify position move
private TreeNode deserial(Queue<String> q) {
String val = q.poll();
if ("#".equals(val)) return null;
TreeNode root = new TreeNode(Integer.valueOf(val));
root.left = deserial(q);
root.right = deserial(q);
return root;
}
}
// Your Codec object will be instantiated and called as such:
// Codec ser = new Codec();
// Codec deser = new Codec();
// TreeNode ans = deser.deserialize(ser.serialize(root));