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

# 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 pathSum(self, root, sum):
        """
        :type root: TreeNode
        :type sum: int
        :rtype: List[List[int]]
        """
        result = []
        self.auxPathSum(root,sum,[],result)
        return result
        
    def auxPathSum(self, root, sum, curList, curLists):
        if root == None:
            return
        sum -= root.val
        if sum == 0 and (root.left == None and root.right == None):
            curLists.append(curList + [root.val])
            return 
        if root.left != None:
            self.auxPathSum(root.left, sum - root.val, curList + [root.val],curLists)
        if root.right != None:
            self.auxPathSum(root.right, sum - root.val, curList + [root.val],curLists)