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 #.
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
/ \_/
很简单，BFS遍历，加上Map来保存label和节点地址
/** * 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; LinkedList<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>(); HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode,UndirectedGraphNode>(); UndirectedGraphNode newHead = new UndirectedGraphNode(node.label); queue.add(node); map.put(node, newHead); while(!queue.isEmpty()){ UndirectedGraphNode curr = queue.pop(); ArrayList<UndirectedGraphNode> currNeighbors = (ArrayList)curr.neighbors; for(UndirectedGraphNode aNeighbor: currNeighbors){ if(!map.containsKey(aNeighbor)){ UndirectedGraphNode copy = new UndirectedGraphNode(aNeighbor.label); map.put(aNeighbor,copy); map.get(curr).neighbors.add(copy); queue.add(aNeighbor); }else{ map.get(curr).neighbors.add(map.get(aNeighbor)); } } } return newHead; } }
原文：http://www.cnblogs.com/qionghua520/p/4385279.html