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题目描述如下：
Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.
Nodes are labeled uniquely.
We use# as a separator for each node, and , as a separator for node label and each neighbor of the node. As an example, consider the serialized graph { 0,1,2#1,2#2,2}.
The graph has a total of three nodes, and therefore contains three parts as separated by #.
0. Connect node 0 to both nodes 1 and 2.1. Connect node 1 to node 2.2. Connect node 2 to node 2 (itself), thus forming a self-cycle.Visually, the graph looks like the following:
1 / \ / \ 0 --- 2 / \ \_/
public class Solution { public static int cycleCount = 0; public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) { HashMap checker = new HashMap (); return cloneGraph(node, checker); } public UndirectedGraphNode cloneGraph(UndirectedGraphNode node, HashMap checker){ if(node == null) return null; if(checker.containsKey(node.label)) return checker.get(node.label); UndirectedGraphNode newNode = new UndirectedGraphNode(node.label); checker.put(node.label, newNode); for(UndirectedGraphNode n : node.neighbors){ newNode.neighbors.add(cloneGraph(n, checker)); } return newNode; }} 转载地址：http://plbvb.baihongyu.com/