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 node 0 to both nodes 1 and 2.
Second node is labeled as 1. Connect node 1 to node 2.
Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
Visually, the graph looks like the following:
1
/ \
/ \
0 --- 2
/ \
\_/
Solution:
/**
* 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;
List<UndirectedGraphNode> oldList = new ArrayList<>();
List<UndirectedGraphNode> newList = new ArrayList<>();
Queue<UndirectedGraphNode> queue = new LinkedList<>();
queue.offer(node);
UndirectedGraphNode clone = new UndirectedGraphNode(node.label);
oldList.add(node);
newList.add(clone);
while(!queue.isEmpty()){
UndirectedGraphNode n = queue.poll();
UndirectedGraphNode c = newList.get(oldList.indexOf(n));
for(UndirectedGraphNode neighbor : n.neighbors){
int idx = oldList.indexOf(neighbor);
if(idx==-1){
UndirectedGraphNode newNode = new UndirectedGraphNode(neighbor.label);
c.neighbors.add(newNode);
queue.offer(neighbor);
oldList.add(neighbor);
newList.add(newNode);
} else {
c.neighbors.add(newList.get(idx));
}
}
}
return clone;
}
}