[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         / \         \_/

思路：复制节点，然后再复制邻居节点，用一个map表示节点是否复制过，如果复制过则跳过

代码：

/** * Definition for undirected graph. * struct UndirectedGraphNode { *     int label; *     vector<UndirectedGraphNode *> neighbors; *     UndirectedGraphNode(int x) : label(x) {}; * }; */class Solution {public:    map<int,UndirectedGraphNode*> lab;        UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {        if(node==NULL) return NULL;        UndirectedGraphNode *res;        res=new UndirectedGraphNode(node->label);        lab[node->label]=res;        for(int i=0;i<node->neighbors.size();i++){            if(lab.find(node->neighbors[i]->label)==lab.end()) res->neighbors.push_back(cloneGraph(node->neighbors[i]));            else res->neighbors.push_back(lab[node->neighbors[i]->label]);        }        return res;    }};