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.
#
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 #
.
- First node is labeled as
0
. Connect node0
to both nodes1
and2
. - Second node is labeled as
1
. Connect node1
to node2
. - Third node is labeled as
2
. Connect node2
to node2
(itself), thus forming a self-cycle.
Visually, the graph looks like the following:
1 / \ / \ 0 --- 2 / \ \_/
Reference: https://www.cnblogs.com/springfor/p/3874591.html
/** * 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; } //queue Queue<UndirectedGraphNode> queue = new LinkedList<>(); //map Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>(); UndirectedGraphNode head = new UndirectedGraphNode(node.label); map.put(node, head); queue.add(node); while(!queue.isEmpty()){ UndirectedGraphNode curnode = queue.poll(); //check each neighbor for(UndirectedGraphNode aneighbor: curnode.neighbors){ //if not visited,then add to queue if(!map.containsKey(aneighbor)){ queue.add(aneighbor); UndirectedGraphNode newneighbor = new UndirectedGraphNode(aneighbor.label); map.put(aneighbor, newneighbor); } map.get(curnode).neighbors.add(map.get(aneighbor)); } } return head; } }