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 #
.
- 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;
}
}