Graph Clone(DFS)

class Solution {
private:
    unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> umap;
public:
// 用DFS
// 用map来存储，key是旧的结点地址，value是新的结点地址
// 第一遍，如果没有访问过，就clone并加入umap
// 第二遍，如果没有访问过，就clone他的neighbors
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if(node == NULL) return NULL;
        DFS(node);
        DFSNei(node);
        return umap[node];
       
    }
    void DFS(UndirectedGraphNode *node){
        umap[node] = new UndirectedGraphNode(node->label); // 访问node
        for(auto nei: node->neighbors){ // 访问与Node相邻的
            if(umap.count(nei) == 0){ // 如果没有访问过
                DFS(nei);
            }
        }
    }
    void DFSNei(UndirectedGraphNode *node){
        for(auto nei: node->neighbors){ // clone umap[node]的neighbors
            umap[node]->neighbors.push_back(umap[nei]);
        }
        for(auto nei: node->neighbors){
            if(!nei->neighbors.empty() && umap[nei]->neighbors.empty()){
               DFSNei(nei);
            }
        }
    }
};