LeetCode Clone Graph

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 #.

1. First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
2. Second node is labeled as 1. Connect node 1 to node 2.
3. 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
         / \
         \_/

HashMap<Integer,UndirectedGraphNode> hashMap = new HashMap<Integer, UndirectedGraphNode>();
	
	public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
		
		if(node==null)return null;
		
		UndirectedGraphNode headGraphNode,tempgGraphNode;
		
		tempgGraphNode = hashMap.get(node.label);
		headGraphNode = new UndirectedGraphNode(node.label);
		headGraphNode.neighbors = new ArrayList<UndirectedGraphNode>();
		hashMap.put(node.label, headGraphNode);
		int n = node.neighbors.size();
		for(int i=0;i<n;i++){
			
			tempgGraphNode = hashMap.get(node.neighbors.get(i).label);
			
			if(tempgGraphNode!=null){
				headGraphNode.neighbors.add(tempgGraphNode);
			}
			else{
				
				tempgGraphNode = cloneGraph(node.neighbors.get(i));
				headGraphNode.neighbors.add(tempgGraphNode);
			}
		}
		
		return headGraphNode;
        
    }