思路：

實在沒能搞懂大佬們的思路，坐等第二遍刷再看吧

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回二維列表，內部每個列表表示找到的路徑
    def FindPath(self, root, expectNumber):
        if not root:
            return []
        tmp = []
        if  not root.left and not root.right and root.val == expectNumber:
            return [[root.val]]
        else:
            left = self.FindPath(root.left,expectNumber-root.val)
            right = self.FindPath(root.right,expectNumber-root.val)
            for item in left+right:
                tmp.append([root.val]+item)
        return tmp