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LeetCode地址：https://leetcode.com/problems/clone-graph/

Problem:
Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

OJ’s undirected graph serialization:
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 #.

  1. First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
  2. Second node is labeled as 1. Connect node 1 to node 2.
  3. Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

   1
  / \
 /   \
0 --- 2
     / \
     \_/

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/**
 * Definition for undirected graph.
 * class UndirectedGraphNode {
 *     int label;
 *     List<UndirectedGraphNode> neighbors;
 *     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
 * };
 */
public class Solution {
    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if(node==null)
            return null;
        
        HashMap<Integer,UndirectedGraphNode> graphMap=new HashMap<Integer,UndirectedGraphNode>();
        Queue<UndirectedGraphNode> visit=new LinkedList<UndirectedGraphNode>();
        UndirectedGraphNode temp;
        
        visit.add(node);
        
        while(!visit.isEmpty())
        {
            temp=visit.poll();
            
            if(!graphMap.containsKey(temp.label))
            {
                UndirectedGraphNode graphNode=new UndirectedGraphNode(temp.label);
                graphMap.put(temp.label, graphNode);
                
                visit.addAll(temp.neighbors);
            }
        }
        
        visit.add(node);
        while(!visit.isEmpty())
        {
            temp=visit.poll();
            UndirectedGraphNode graphNode=graphMap.get(temp.label);
            if(graphNode.neighbors.size()==0 && temp.neighbors.size()!=0)
            {
                for(UndirectedGraphNode neighbor:temp.neighbors)
                {
                    graphNode.neighbors.add(graphMap.get(neighbor.label));
                    visit.add(neighbor);
                }
            }
        }
        
        return graphMap.get(node.label);
    }
}

本作品采用[知识共享署名-非商业性使用-相同方式共享 2.5]中国大陆许可协议进行许可，我的博客欢迎复制共享，但在同时，希望保留我的署名权kubiCode，并且，不得用于商业用途。如您有任何疑问或者授权方面的协商，请给我留言。

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