Leetcode Problem : Clone Graph

Clone Graph

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


OJ's undirected graph serialization:
Nodes are labeled uniquely.

We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.
As an example, consider the serialized graph {0,1,2#1,2#2,2}.

The graph has a total of three nodes, and therefore contains three parts as separated by #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
Second node is labeled as 1. Connect node 1 to node 2.
Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
Visually, the graph looks like the following:

       1
      / \
     /   \
    0 --- 2
         / \
         \_/

Code

void DFS_cg(UndirectedGraphNode *v1,UndirectedGraphNode *v2,map<UndirectedGraphNode *,UndirectedGraphNode *>& nodeMap){
    vector<UndirectedGraphNode *>::const_iterator it = v1->neighbors.begin();
    for(; it != v1->neighbors.end(); ++it){
        UndirectedGraphNode *w1 = *it;
        if(nodeMap.find(w1) == nodeMap.end()){
            UndirectedGraphNode *w2 = new UndirectedGraphNode(w1->label);
            v2->neighbors.push_back(w2);
            nodeMap.insert(make_pair(w1,w2));
            DFS_cg(w1,w2,nodeMap);
        }
        else{
            UndirectedGraphNode *w2 = nodeMap[w1];
            v2->neighbors.push_back(w2);
        }
    }
}
UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
// Note: The Solution object is instantiated only once and is reused by each test case.
    if(!node)
        return 0;
    map<UndirectedGraphNode *,UndirectedGraphNode *> nodeMap;  
    UndirectedGraphNode *u = new UndirectedGraphNode(node->label);
    nodeMap.insert(make_pair(node,u));
    DFS_cg(node,u,nodeMap);
    return u;
}