Leetcode练习(Python)：树类：第113题： 路径总和 II：给定一个二叉树和一个目标和，找到所有从根节点到叶子节点路径总和等于给定目标和的路径。 说明: 叶子节点是指没有子节点的节点。

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

class Solution:
    def pathSum(self, root: TreeNode, sum_: int) -> List[List[int]]:
        if not root:
            return []
        result = []
        stack_sum = []
        stack_node = []
        stack_sum.append([root.val])
        stack_node.append(root)
        while stack_sum and stack_node:
            auxiliary_sum = stack_sum.pop()
            auxiliary_node = stack_node.pop()
            if auxiliary_node.left:
                stack_sum.append(auxiliary_sum + [auxiliary_node.left.val])
                stack_node.append(auxiliary_node.left)
            if auxiliary_node.right:
                stack_sum.append(auxiliary_sum + [auxiliary_node.right.val])
                stack_node.append(auxiliary_node.right)
            if not auxiliary_node.left and not auxiliary_node.right and sum(auxiliary_sum) == sum_:
                result.append(auxiliary_sum)
        return result