257. Binary Tree Paths

题目

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

1 /
2 3
5

All root-to-leaf paths are: ["1->2->5", "1->3"]

Credits:Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

解题思路

见程序注释