【leetcode】1161. Maximum Level Sum of a Binary Tree

题目如下：

解题思路：没什么好说的，依次计算出每一层的值，求出最大即可。

代码如下：

# Definition for a binary tree node.

# class TreeNode(object):

#     def __init__(self, x):

#         self.val = x

#         self.left = None

#         self.right = None

class Solution(object):

    dic = {}

    def recursive(self,node,level):

        self.dic[level] = self.dic.setdefault(level,0) + node.val

        if node.left != None:

            self.recursive(node.left,level+1)

        if node.right != None:

            self.recursive(node.right,level+1)

    def maxLevelSum(self, root):

        """

        :type root: TreeNode

        :rtype: int

        """

        self.dic = {}

        self.recursive(root,1)

        max_val = 0

        res = 0

        for key,val in self.dic.iteritems():

            if max_val < val:

                max_val = val

                res = key

        return res