answer.py

#!/usr/bin/env python

#-------------------------------------------------------------------------------
# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def hasPathSum(self, root, sum):
        """
        :type root: TreeNode
        :type sum: int
        :rtype: bool
        """
        
        if root is None:
            return False
        elif root.left is None and root.right is None and sum == root.val:
            return True
        else:
            return self.hasPathSum(root.left, sum - root.val) or self.hasPathSum(root.right, sum - root.val)
#-------------------------------------------------------------------------------
# Testing