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 

#

.
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
/ \
\_/

/**
* Definition for undirected graph.
* struct UndirectedGraphNode {
*     int label;
*     vector<UndirectedGraphNode *> neighbors;
*     UndirectedGraphNode(int x) : label(x) {};
* };
*/
class Solution {
public:
UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
// Note: The Solution object is instantiated only once.
if(node == NULL)return NULL;

queue<UndirectedGraphNode*> qu;
qu.push(node);
set<UndirectedGraphNode*> st;
while(!qu.empty())
{
UndirectedGraphNode* curnode = qu.front();
qu.pop();
if(st.find(curnode) != st.end()) continue;
st.insert(curnode);
vector<UndirectedGraphNode *>::iterator it = curnode->neighbors.begin();
while(it != curnode->neighbors.end())
{
qu.push(*it);
it++;
}
}

map<UndirectedGraphNode*, UndirectedGraphNode*> graphmp;
set<UndirectedGraphNode*>::iterator sit = st.begin();
for(;sit!=st.end();sit++)
{
UndirectedGraphNode* tmp = new UndirectedGraphNode((*sit)->label);
graphmp[*sit] = tmp;
}

sit = st.begin();
for(;sit!=st.end();sit++)
{
UndirectedGraphNode* tmp = graphmp[*sit];
vector<UndirectedGraphNode *>::iterator vit = (*sit)->neighbors.begin();
while(vit != (*sit)->neighbors.end())
{
tmp->neighbors.push_back(graphmp[(*vit)]);
vit++;
}
}

return graphmp[node];
}
};