[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

         / \

         \_/

DFS!

 1 /**

 2  * Definition for undirected graph.

 3  * struct UndirectedGraphNode {

 4  *     int label;

 5  *     vector<UndirectedGraphNode *> neighbors;

 6  *     UndirectedGraphNode(int x) : label(x) {};

 7  * };

 8  */

 9 class Solution {

10 public:

11     void cloneNode(UndirectedGraphNode *&res, UndirectedGraphNode *node, map<int, UndirectedGraphNode*> &mp) {

12         if (mp[node->label] != NULL) {

13             res = mp[node->label];

14             return;

15         }

16         res = new UndirectedGraphNode(node->label);

17         res->neighbors.resize(node->neighbors.size());

18         mp[node->label] = res;

19 

20         for (int i = 0; i < node->neighbors.size(); ++i) {

21             cloneNode(res->neighbors[i], node->neighbors[i], mp);

22         }

23     }

24     

25     UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {

26         if (node == NULL) return NULL;

27         map<int, UndirectedGraphNode*> mp;

28         UndirectedGraphNode* res; 

29         cloneNode(res, node, mp);

30         return res;

31     }

32 };