247. Serialize and Deserialize Binary Tree

Hard · Binary Tree

Design an algorithm to serialize a binary tree to a string and deserialize that string back to the original tree. There is no constraint on the serialization format.

Examples

Example 1
Input: Tree: 1→(2, 3→(4,5))
Output: "1,2,null,null,3,4,null,null,5,null,null"
Explanation: Pre-order serialisation with null markers

Constraints

• Tree nodes: 0 to 10⁴, -1000 ≤ val ≤ 1000