100. Same Tree

Description:

https://leetcode.com/problems/same-tree/description/

In this problem, we are gonna check the identical structure and their values. Two tree must the same tree structurely. 

Solution:

Recursion Method

* First condition checks "both p and q are None." If it is return True.

 

* Second condition checks "one of p and q are None." If it is, then return False.

--> The reason is that just one of p or q done, that menas both tree don't have identical structure.

 

* Third condition checks "if both p node and q node are same, we step to the child node, recursively.

We are gonna see the both right child and left child of p and q. 

 

When we reach out the last node of p and q, their child node is None. In conclusion, we met the first condition again which is "both p and q are None."