[Leetcode] Clone Graph

Clone Graph

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

Analysis: 
A typical graph problem, either DFS or BFS does the trick.

Solution:
class Solution {
public:
    UndirectedGraphNode *DFS(UndirectedGraphNode *node, unordered_map<int, UndirectedGraphNode*> &visited)
    {
        UndirectedGraphNode *ret = new UndirectedGraphNode(node->label);
        visited[node->label] = ret;
        
        for(int i = 0; i < node->neighbors.size(); i++)
        {
            UndirectedGraphNode *temp = node->neighbors[i];
            if(visited[temp->label])
            {
               ret->neighbors.push_back(visited[temp->label]); 
            }
            else
            {
               ret->neighbors.push_back(DFS(node->neighbors[i], visited));
            }
        }
        return ret;
    }
    
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if(node == NULL)
           return NULL;
       UndirectedGraphNode *ret;
       unordered_map<int, UndirectedGraphNode*> visited; 
       ret = DFS(node, visited);
       return ret; 
    }

};