【leetcode_easy_string】606. Construct String from Binary Tree

problem

​​606. Construct String from Binary Tree​​

solution#1: 使用原函数递归；

code

solution#2: 使用额外函数递归；

code

参考

1. ​​leetcode_easy_string_606. Construct String from Binary Tree​​;

2. ​​Grandyang​​;

完