[leetcode]Q133Clone Graph

克隆图记住：一个map一个queue，照葫芦画瓢BFS

找到一个节点就画一个对应的新的，用map对应，然后添加邻居，记录邻居到queue

public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if (node==null) return node;
        UndirectedGraphNode res = new UndirectedGraphNode(node.label);
        Queue<UndirectedGraphNode> queue = new LinkedList<>();
        Map<UndirectedGraphNode,UndirectedGraphNode> map  = new HashMap<>();
        queue.offer(node);
        map.put(node,res);
        while (!queue.isEmpty()){
            UndirectedGraphNode cur = queue.poll();
            List<UndirectedGraphNode> neighbors = cur.neighbors;
            for (UndirectedGraphNode neighbor :
                    neighbors) {
                if (!map.containsKey(neighbor)){
                    UndirectedGraphNode newNode = new UndirectedGraphNode(neighbor.label);
                    queue.offer(neighbor);
                    //在旧图中每遍历到一个节点，就在map中给新图申请一个对应的内存
                    map.put(neighbor,newNode);
                }
                //根据旧图中的位置为新图添加邻居
                map.get(cur).neighbors.add(map.get(neighbor));
            }
        }
        return res;
    }