257 - Binary Tree Paths

2020/11/22

leetcode

Problem

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

Note: A leaf is a node with no children.

Example:

Input:

   1
 /   \
2     3
 \
  5

Output: ["1->2->5", "1->3"]

Explanation: All root-to-leaf paths are: 1->2->5, 1->3

Solution

class Solution:
    def binaryTreePaths(self, root: TreeNode) -> List[str]:
        if not root:
            return []

        if not root.right and not root.left:
            return [str(root.val)]

        paths = [str(root.val) + "->" + s for s in self.binaryTreePaths(root.right) + self.binaryTreePaths(root.left)]
        return paths