参考代码:
class TreeNode:
def __init__(self, val):
self.val = val
self.left, self.right = None, None
class Solution:
def levelSum(self, root, level):
p = []
self.dfs(root, p, 1, level)
return sum(p)
def dfs(self, root, p, dep, level):
if root is None:
return
if dep == level:
p.append(root.val)
return
self.dfs(root.left, p, dep + 1, level)
self.dfs(root.right, p, dep + 1, level)