Leetcode-133. Clone Graph

133. Clone Graph

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

目标：克隆一个无向图，其中，图的节点由以下结构表示。

• Definition for undirected graph.
• struct UndirectedGraphNode {
• int label;
• vector<UndirectedGraphNode *> neighbors;
• UndirectedGraphNode(int x) : label(x) {};

• };

  在solution里添加一个map<UndirectedGraphNode *, UndirectedGraphNode *> m来保存克隆图（Key 为节点，Value 为该节点的邻接节点）。用DFS算法遍历全图，若当前节点已在克隆图中，则返回克隆图中的该节点，否则创立新节点加入克隆图中，并添加其所有邻接节点。

class Solution {  public:      UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {          if(!node)             return NULL;          if(m.count(node))             return m[node];          UndirectedGraphNode *nodeClone = new UndirectedGraphNode(node->label);        m[node] = nodeClone;        for(int i=0;i<node->neighbors.size();i++)          {            UndirectedGraphNode *temp = cloneGraph(node->neighbors[i]);            if(temp != NULL)                nodeClone->neighbors.push_back(temp);        }        return nodeClone;    }  private:      map<UndirectedGraphNode *, UndirectedGraphNode *> m;  };