原题链接

 1 class Solution:
 2     def pathSum(self, root: TreeNode, sum: int) -> List[List[int]]:
 3         ans,tmp = [],[]
 4         def helper(root,sum):
 5             if not root:return
 6             tmp.append(root.val)
 7             sum -= root.val
 8             helper(root.left,sum)
 9             helper(root.right,sum)
10             if not root.left and not root.right and 0 == sum:
11                 ans.append(tmp[:])
12             tmp.pop()
13         helper(root,sum)
14         return ans
15