多叉树的直径

# class Interval:
#     def __init__(self, a=0, b=0):
#         self.start = a
#         self.end = b

#
# 树的直径
# @param n int整型 树的节点个数
# @param Tree_edge Interval类一维数组 树的边
# @param Edge_value int整型一维数组 边的权值
# @return int整型
#
from collections import defaultdict        
class Solution:
    def solve(self , n , Tree_edge , Edge_value ):
        # write code here
        graph, table = {}, defaultdict()
        for i in range(len(Tree_edge)):
            graph.setdefault(Tree_edge[i].start, []).append(Tree_edge[i].end), graph.setdefault(Tree_edge[i].end, []).append(Tree_edge[i].start)
            table[(Tree_edge[i].start, Tree_edge[i].end)], table[(Tree_edge[i].end, Tree_edge[i].start)] = Edge_value[i], Edge_value[i]
        self.res, self.maxIndex =  0, -1
        def dfs(cnt, node, parent):
            cur = graph[node]
            for i in range(len(cur)):
                if cur[i] == parent:
                    continue
                dfs(cnt+table[(node,cur[i])], cur[i], node)
            if cnt > self.res:
                self.res = cnt
                self.maxIndex = node
        
        dfs(0, 0, -1)
        dfs(0, self.maxIndex, -1)
        return self.res