题目来源：
https://leetcode.com/problems/clone-graph/
题意分析：
克隆一个无向图。每个节点包括一个数值和它的邻居。
题目思路：
直接深度拷贝。
代码（python）：
# Definition for a undirected graph node # class UndirectedGraphNode(object): # def __init__(self, x): # self.label = x # self.neighbors = []class Solution(object):def cloneGraph(self, node):""":type node: UndirectedGraphNode:rtype: UndirectedGraphNode"""if node == None:return noded = {}def dfs(n):if n in d:return d[n]ans = UndirectedGraphNode(n.label)d[n] = ansfor i in n.neighbors:ans.neighbors.append(dfs(i))return ansreturn dfs(node)
