题目链接：https://leetcode.com/problems/clone-graph/
题目：
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
/ \_/
思路：
BFS/DFS ，因为标签唯一，所以用Map保存对应关系，这里用dfs递归拷贝新节点。
算法：
Map<Integer, UndirectedGraphNode> sets = new HashMap<Integer, UndirectedGraphNode>();
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if(node == null)
return null;
if(sets.containsKey(node.label))
return sets.get(node.label);
UndirectedGraphNode newNode = new UndirectedGraphNode(node.label);
sets.put(newNode.label, newNode);
for (UndirectedGraphNode neighbor : node.neighbors) {
newNode.neighbors.add(cloneGraph(neighbor));
}
return newNode;
} 原文：http://blog.csdn.net/yeqiuzs/article/details/51542415