Clone Graph

BFS 用hashmap记录对应关系

public class Solution {
    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(node == null)
            return null;
        LinkedList<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>();
        Map<UndirectedGraphNode, UndirectedGraphNode> mymap = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
        UndirectedGraphNode head = new UndirectedGraphNode(node.label);
        queue.add(node);
        mymap.put(node, head);
        while(!queue.isEmpty())
        {
            UndirectedGraphNode nodeinqueue = queue.poll();
            for(UndirectedGraphNode i:nodeinqueue.neighbors)
            {
                if(mymap.containsKey(i))
                    mymap.get(nodeinqueue).neighbors.add(mymap.get(i));
                else
                {
                    UndirectedGraphNode tmp = new UndirectedGraphNode(i.label);
                    mymap.get(nodeinqueue).neighbors.add(tmp);
                    mymap.put(i, tmp);
                    queue.add(i);
                }
            }
        }
        return head;
    }
}