过遍数

对于做过的题，一定要过遍数！！！

/**
 * 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 node;
        }
        Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();
        Queue<UndirectedGraphNode> queue = new LinkedList<>();
        UndirectedGraphNode cloneNode = new UndirectedGraphNode(node.label);
        queue.offer(node);
        map.put(node, cloneNode);
        while (!queue.isEmpty()) {
            UndirectedGraphNode curNode = queue.poll();
            UndirectedGraphNode curNodeClone = map.get(curNode);
            for (UndirectedGraphNode curNodeNeighbor: curNode.neighbors) {
                if (map.containsKey(curNodeNeighbor)) {
                    UndirectedGraphNode curNodeNeighborClone = map.get(curNodeNeighbor);
                    curNodeClone.neighbors.add(curNodeNeighborClone);
                } else {
                    UndirectedGraphNode curNodeNeighborClone = new UndirectedGraphNode(curNodeNeighbor.label);
                    curNodeClone.neighbors.add(curNodeNeighborClone);
                    map.put(curNodeNeighbor, curNodeNeighborClone);
                    queue.offer(curNodeNeighbor);
                }
            }
        }
        return cloneNode;
    }
}