leetcode 133. Clone Graph

class Solution {public:UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node){if (node == nullptr){return nullptr;}if (map.find(node) == map.end()){map[node] = new UndirectedGraphNode(node->label);for (auto a : node->neighbors){map[node]->neighbors.push_back(cloneGraph(a));}}return map[node];}private:unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> map;};