[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:

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 };