Hard · Trees

Serialize and Deserialize Binary Tree

Design a Codec for binary trees. serialize(root) turns a tree into a string, and deserialize(data) rebuilds a tree from such a string, so that deserialize(serialize(root)) has exactly the same shape and values as root. Any string format is allowed; the reference writes a preorder walk with "null" for every missing child.

[1,2,3,null,null,4,5]

[5,3,8,1,4]