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 #.
0. Connect node 0 to both nodes 1 and 2.1. Connect node 1 to node 2.2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
Visually, the graph looks like the following:
1 / / 0 --- 2 / \_/
地址：https://oj.leetcode.com/problems/clone-graph/
算法：把整个图复制下来，基本就是利用map来完成的，复制的过程采用递归完成。代码：
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 UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
12 if(!node){
13 return NULL;
14 }
15 map<int,UndirectedGraphNode *> hash_table;
16 set<int> isTraved;
17 return subClone(node,hash_table,isTraved);
18 }
19 UndirectedGraphNode *subClone(UndirectedGraphNode *node, map<int,UndirectedGraphNode*> &hash_table, set<int> &isTraved){
20 if(!node){
21 return NULL;
22 }
23 int label = node->label;
24 if(isTraved.find(label) != isTraved.end()){
25 return hash_table[label];
26 }
27 if(hash_table.find(label) == hash_table.end()){
28 hash_table[label] = new UndirectedGraphNode(label);
29 }
30 isTraved.insert(label);
31 UndirectedGraphNode *p = hash_table[label];
32 vector<UndirectedGraphNode *>::iterator it = node->neighbors.begin();
33 for(; it != node->neighbors.end(); ++it){
34 p->neighbors.push_back(subClone(*it,hash_table,isTraved));
35 }
36 return p;
37 }
38 };
原文：http://www.cnblogs.com/boostable/p/leetcode_clone_graph.html