297. Serialize and Deserialize Binary Tree

Description:

Solution:

serialize()

if node is None --> append('n')

if node exist --> append(str(node.val))

We should search from left!

','.join(res) => ['a', 'b', 'c'] --> "a,b,c"

 

deserialize()

data.split(",") => "a,b,c" --> ['a', 'b', 'c']

self.i is the global variable

'n' means null, so return null. Don't forgetself.i += 1

We are gonna append TreeNode object. '(val)' is the string form, so we should change the type int.

Don't forget, do left first. 

After loop, we are gonna return dfs().