Binary Tree Paths

binary_tree_paths.py

"""
Description:
Given a binary tree, return all root-to-leaf paths. A leaf is a node with no children.

Example:
Input:

   1
 /   \
2     3
 \
  5

Output: ["1->2->5", "1->3"]
"""
class TreeNode:
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

def binaryTreePaths(root):
    """
    :type root: TreeNode
    :rtype: List[str]
    """
    def walk(root, path, result):
        path += str(root.val)
        if not root.left and not root.right:
            result.append(path)
        if root.left:
            walk(root.left, path+'->', result)
        if root.right:
            walk(root.right, path+'->', result)
    result = []
    if not root: return result
    walk(root, '', result)
    return result