【LeetCode】133. Clone Graph

Description:

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         / \         \_/

题目要求：克隆无向图

该题可采用深度优先算法一边遍历一边复制即可。

映射表m用来保存原图结点与克隆结点的对应关系。

映射表visited用来记录已经访问过的原图结点，防止循环访问。

队列q用于记录广度优先遍历的层次信息

Solutions：

class Solution {
public:
    map<UndirectedGraphNode *, UndirectedGraphNode *> m;
    
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) 
    {
        if(node == NULL)
            return NULL;
        
        if(m.find(node) != m.end())   //if node is visited, just return the recorded nodeClone
            return m[node];
            
        UndirectedGraphNode *nodeClone = new UndirectedGraphNode(node->label);
        m[node] = nodeClone;
        for(int st = 0; st < node->neighbors.size(); st ++)
        {
            UndirectedGraphNode *temp = cloneGraph(node->neighbors[st]);
            if(temp != NULL)
                nodeClone->neighbors.push_back(temp);
        }
        return nodeClone;
    }
};