LeetCode113. 路径总和 II

 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:
11                 if 0 == sum:
12                     ans.append(tmp[::])
13             tmp.pop()
14         helper(root,sum)
15         return ans