LeetCode-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 #.

1. First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
2. Second node is labeled as 1. Connect node 1 to node 2.
3. 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
         / \
         \_/

class Solution {
public:
    void Sub(map<UndirectedGraphNode*,UndirectedGraphNode*>& se,UndirectedGraphNode** nnode,UndirectedGraphNode*node){
            (*nnode)=new UndirectedGraphNode(node->label);
            se[node]=(*nnode);
            for(int i=0;i<node->neighbors.size();i++){
                if(se.find(node->neighbors[i])==se.end()){
                    UndirectedGraphNode * n;
                    Sub(se,&n,node->neighbors[i]);
                    (*nnode)->neighbors.push_back(n);
                }
                else{
                    (*nnode)->neighbors.push_back(se[node->neighbors[i]]);
                }
            }
    }
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if(node==NULL)return NULL;
        UndirectedGraphNode * ret=NULL;
        map<UndirectedGraphNode *,UndirectedGraphNode*>se;
        Sub(se,&ret,node);
        return ret;
    }
};