leetcode 113.路径总和 II

113.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。

叶子节点：没有子节点的节点。

              5
             / \
            4   8
           /   / \
          11  13  4
         /  \    / \
        7    2  5   1       sum=22

[
   [5,4,11,2],
   [5,8,4,5]
]                           返回

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def pathSum(self, root: TreeNode, s: int) -> List[List[int]]:
        if not root:
            return []
        res = []
        stack = [(root, [root.val])]  # （当前节点，路径数组[]）
        while stack:
            cur, ls = stack.pop()
            if not cur.left and not cur.right and sum(ls) == s:
                res.append(ls)
            if cur.right:
                stack.append((cur.right, ls + [cur.right.val]))
            if cur.left:
                stack.append((cur.left, ls + [cur.left.val]))
        return res
#  DFS + stack