113 path sum ii
113. Path Sum II
题目：
https://leetcode.com/problems/path-sum-ii/
tag : DFS
难度 : Medium
注意宁愿写几次curList + [root.val] 也不要直接传一个list进去，因为list pass by reference的亏已经吃过了
class Solution(object):
def pathSum(self, root, sum):
"""
:type root: TreeNode
:type sum: int
:rtype: List[List[int]]
"""
res = []
self.auxPathSum(root, sum, [], res)
return res
def auxPathSum(self, root, sum, cur_list, cur_lists):
if not root:
return
sum -= root.val
if sum == 0 and not root.left and not root.right:
cur_lists.append(cur_list + [root.val])
return
if root.left:
self.auxPathSum(root.left, sum, cur_list + [root.val], cur_lists)
if root.right:
self.auxPathSum(root.right, sum, cur_list + [root.val], cur_lists)
