112.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-


__author__ = ['"wuyadong" <wuyadong311521@gmail.com>']


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


class Solution(object):
    def hasPathSum(self, root, sum):
        """
        :type root: TreeNode
        :type sum: int
        :rtype: bool
        """
        if root is None:
            return False

        if root.left is None and root.right is None:
            if sum == root.val:
                return True
            else:
                return False

        if root.left and self.hasPathSum(root.left, sum-root.val):
            return True
        if root.right and self.hasPathSum(root.right, sum-root.val):
            return True

        return False