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 { public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) { if (node == null) { return null; } Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>(); Set<UndirectedGraphNode> visited = new HashSet<>(); Queue<UndirectedGraphNode> toBeVisited = new LinkedList<>(); toBeVisited.offer(node); while (!toBeVisited.isEmpty()) { UndirectedGraphNode current = toBeVisited.poll(); if (visited.contains(current)) { continue; } if (map.get(current) == null) { map.put(current, new UndirectedGraphNode(current.label)); } for (UndirectedGraphNode neighbor : current.neighbors) { if (map.get(neighbor) == null) { map.put(neighbor, new UndirectedGraphNode(neighbor.label)); } map.get(current).neighbors.add(map.get(neighbor)); toBeVisited.offer(neighbor); } visited.add(current); } return map.get(node); } }
原文：http://www.cnblogs.com/chencode/p/clone-graph.html