Clone Graph [Leetcode解题报告]

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     / \     \_/

这道题我主要用的是BFS方法，利用map标记新图的node。在此题中我用的map<int,UndirectedGraphNode*>（代码1），也可以用map<UndirectedGraphNode*,UndirectedGraphNode*>，后面那个更快些，也烧脑一些，见代码2：
代码1：

 UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {         queue<UndirectedGraphNode*> q_ori;         UndirectedGraphNode *newNode=NULL,*temp=NULL,*p=NULL;         unordered_map<int,UndirectedGraphNode*> m;         int temp_label=0;         if(node==NULL)return NULL;         temp_label=node->label;         newNode=new UndirectedGraphNode(temp_label);         m[temp_label]=newNode;         q_ori.push(node);         while(!q_ori.empty()){            temp=q_ori.front();            temp_label=temp->label;            q_ori.pop();            newNode=m[temp_label];            for(int i=0;i<temp->neighbors.size();i++){                int temp_nei_label=temp->neighbors[i]->label;                if(m.find(temp_nei_label)==m.end()){                     p=new UndirectedGraphNode(temp_nei_label);                     newNode->neighbors.push_back(p);                     m[temp_nei_label]=p;                     q_ori.push(temp->neighbors[i]);                }else{                    newNode->neighbors.push_back(m[temp_nei_label]);                }            }         }         return m[node->label];    }

代码2：

unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> hash;    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {       if (!node) return node;       if(hash.find(node) == hash.end()) {           hash[node] = new UndirectedGraphNode(node -> label);           for (auto x : node -> neighbors) {                (hash[node] -> neighbors).push_back( cloneGraph(x) );           }       }       return hash[node];    }