Tips

不管题目多简单，也一定要step by step. 思维不要偷懒。

- Sum Root to Leaf Numbers(hehehe)

How to describe a code?

1. start from function signature.

   input, return type, variable relationship

2. Two timestamp
   1. before entering function;
   2. after finishing function;

How to descirbe a relatively complex problem ?

• 举个栗子

Implementation Level

• 写Code不要一上来就追求简洁(比如少用variable)，应该保证先把所有信息都传递了，可以写完优化，但是过多考虑这些细节可能会影响思路，即便是在简单的题。(post+in reconstruction).

Class Design

• declare function signature
• make your assumption