LeetCode-113、路径总和 II-中等
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。
示例：
给定如下二叉树，以及目标和 sum = 22，
5
/ \
4 8
/ / \
11 13 4
/ \ / \
7 2 5 1返回:
[
[5,4,11,2],
[5,8,4,5]
]代码：
# 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]]:
def func(cur, path, num):
path.append(cur.val)
if cur.val == num and cur.left is None and cur.right is None:
road.append(path)
if cur.left:
func(cur.left, path[:], num-cur.val)
if cur.right:
func(cur.right, path[:], num-cur.val)
road = []
if root:
func(root, [], sum)
return road
