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     / \     \_/

题目要求克隆图，采用深度优先或者广度优先进行遍历。使用一个Map存储原始节点和克隆以后的节点。

参考代码（使用深度优先遍历）：

/** * Definition for undirected graph. * struct UndirectedGraphNode { *     int label; *     vector<UndirectedGraphNode*> neighbors; *     UndirectedGraphNode(int x) : label(x) {}; * }; */class Solution {public:    UndirectedGraphNode* cloneGraph(UndirectedGraphNode* node)     {        if (node == nullptr)    return nullptr;        // map的key为原始节点，value为拷贝的节点        unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> copyMap;        // 完成给定节点的图的拷贝工作        clone(node, copyMap);        return copyMap[node];    }private:    static UndirectedGraphNode* clone(UndirectedGraphNode* node, unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> &copyMap)    {        // 如果该节点已经拷贝过，直接返回该节点的拷贝        if (copyMap.find(node) != copyMap.end())  return copyMap[node];        // 否则，拷贝该节点及其相邻节点        UndirectedGraphNode* copiedNode = new UndirectedGraphNode(node->label);        copyMap[node] = copiedNode;        for (auto neighborNode : node->neighbors)            copiedNode->neighbors.push_back(clone(neighborNode, copyMap));        return copiedNode;    }};