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
         / \
         \_/

/**
 * 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];
    }
};