Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.
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
/ \_/
思想： 简单纯粹的深度优先搜索。
/**
* Definition for undirected graph.
* struct UndirectedGraphNode {
* int label;
* vector<UndirectedGraphNode *> neighbors;
* UndirectedGraphNode(int x) : label(x) {};
* };
*/
typedef UndirectedGraphNode NODE;
typedef pair<NODE*, NODE*> PAIR;
NODE* dfs(NODE *node, unordered_map<NODE*, NODE*> &_map) {
if(_map.count(node)) return _map[node];
NODE *p = new NODE(node->label);
_map.insert(PAIR(node, p));
for(size_t i = 0; i < node->neighbors.size(); ++i) {
p->neighbors.push_back(dfs(node->neighbors[i], _map));
}
return p;
}
class Solution {
public:
UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
unordered_map<NODE*, NODE*> _map;
_map[NULL] = NULL;
return dfs(node, _map);
}
};
原文：http://www.cnblogs.com/liyangguang1988/p/3938372.html