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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
/ \_/
/** * Definition for undirected graph. * class UndirectedGraphNode { * int label; * List<UndirectedGraphNode> neighbors; * UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); } * }; */ public class Solution { 使用深度优先搜索。这样可以递归实现，如果是宽度优先，就要额外使用queue容器。 关键点： 1 这里的clone需要深度拷贝，就是要使用new操作了 2 防止回路无限循环，就要使用hash表，这里使用map记录访问过的节点。因为这里的label应该是唯一的才对，所以可以直接使用label作为关键字就可以。 public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) { if(node==null) return null; HashMap<Integer,UndirectedGraphNode> map=new HashMap<Integer,UndirectedGraphNode>(); return clone(node,map); } public UndirectedGraphNode clone(UndirectedGraphNode node,HashMap<Integer,UndirectedGraphNode> map){ if(map.containsKey(node.label)) return map.get(node.label); UndirectedGraphNode newNode=new UndirectedGraphNode(node.label); map.put(node.label,newNode);////注意标记的位置 for(UndirectedGraphNode n:node.neighbors){ newNode.neighbors.add(clone(n,map));///// } return newNode; } }
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原文地址：http://www.cnblogs.com/qiaomu/p/4677942.html
