Clone Graph

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

/**
 * Definition for undirected graph.
 * struct UndirectedGraphNode {
 *     int label;
 *     vector<UndirectedGraphNode *> neighbors;
 *     UndirectedGraphNode(int x) : label(x) {};
 * };
 */
class Solution{
public:
    UndirectedGraphNode* cloneGraph(UndirectedGraphNode* node){
        unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> record;
        if(!node)
            return node;
        queue<UndirectedGraphNode*> queue;
        queue.push(node);
        while(!queue.empty()){
            UndirectedGraphNode* nextNode = queue.front();
            queue.pop();
            if(!record.count(nextNode)){
                UndirectedGraphNode* newNode = 
                    new UndirectedGraphNode(nextNode->label);
                record[nextNode] = newNode;
            }
            for(int i=0;i<nextNode->neighbors.size();i++){
                UndirectedGraphNode* childNode = nextNode->neighbors[i];
                if(!record.count(childNode)){
                    UndirectedGraphNode* newNode = 
                        new UndirectedGraphNode(childNode->label);
                    record[childNode] = newNode;
                    queue.push(childNode);
                }
                record[nextNode]->neighbors.push_back(record[childNode]);
            }
        }
        return record[node];
    }
};