小黑除夕跟尚香吃喜茶喝火锅，走了一下午，晚上休息会儿顺便的leetcode之旅:剑指 Offer 34. 二叉树中和为某一值的路径

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阿里云国际，腾讯云国际，低至75折。AWS 93折免费开户实名账号代冲值优惠多多微信号：monov8 飞机：@monov6

小黑代码

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def pathSum(self, root: TreeNode, target: int) -> List[List[int]]:
        paths = []
        def dfs(node, path = []):
            # 递归出口
            if not node:
                return
            path.append(node.val)
            # 递归出口
            if not (node.left or node.right) and sum(path) == target:
                paths.append(path[:])
            dfs(node.left)
            dfs(node.right)
            path.pop()
        dfs(root)
        return paths

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层次遍历法

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def pathSum(self, root: TreeNode, target: int) -> List[List[int]]:
        if not root:
            return []
        # 初始化队列
        q = collections.deque([root])
        q_sum = collections.deque([root.val])
        # node:parent
        map_ = collections.defaultdict(lambda:None)
        arr = []
        while q:
            # 出队
            top = q.popleft()
            top_num = q_sum.popleft()
            # 判断是否叶子结点并输出结点
            if not (top.left or top.right) and top_num == target:
                arr.append(top)
                continue

            # 入队操作
            if top.left:
                q.append(top.left)
                q_sum.append(top.left.val + top_num)
                map_[top.left] = top
            if top.right:
                q.append(top.right)
                q_sum.append(top.right.val + top_num)
                map_[top.right] = top
        # 输出路径
        results = []
        for node in arr:
            path = []
            while node:
                path.append(node.val)
                node = map_[node]
            results.append(path[::-1])
        return results