This problem was asked by Google.

Given the root to a binary tree, implement serialize(root), which serializes the tree into a string, and deserialize(s), which deserializes the string back into the tree.

For example, given the following Node class

class Node: def init(self, val, left=None, right=None): self.val = val self.left = left self.right = right The following test should pass:

node = Node(‘root’, Node(‘left’, Node(‘left.left’)), Node(‘right’)) assert deserialize(serialize(node)).left.left.val == ‘left.left’


This one is weird. It doesn’t say we can’t use standard library, so I will just use it.


type node struct {
	Value string `json:"value"`
	Left  *node  `json:"left"`
	Right *node  `json:"right"`

// New is a node constructor.
func New(v string, l, r *node) *node {
	return &node{
		Value: v,
		Left:  l,
		Right: r,

// Serialize returns string representation of a node.
func (n *node) Serialize() (string, error) {
	b, err := json.Marshal(n)
	return string(b), err

// Deserialize returns node from it's string representation.
func Deserialize(s string) (*node, error) {
	n := new(node)
	return n, json.Unmarshal([]byte(s), n)