LEETCODE : clone-graph(图）

这个题目录了个小视频来说明，地址： https://www.bilibili.com/video/BV1AQ4y1K7wF/

 题目描述

本题要求复制一个无向图，图中每个节点都包含一个标签和它的邻居列表

我们无向图用以下的方法序列化：

• 节点的标签是互不相同的，
• 我们使用“#”作为节点之间的分隔符，使用“,”作为节点标签和节点的节点邻居的分隔符。

例如：现在有一个序列化的无向图{0,1,2#1,2#2,2}.

这个无向图一共有3个节点，因此序列被#分隔成三部分

1. 第一个节点的标签是0，节点0和节点1，节点2之间有边
2. 第二个节点的标签是1，节点1和节点2之间有边
3. 第三个节点的标签是2，节点2和节点2（它自己）之间有边，形成了自环

这个无向图如下图所示

       1↵      / ↵     /   ↵    0 --- 2↵         / ↵         \_/↵

 

 

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 nodes1and2.
2. Second node is labeled as1. Connect node1to node2.
3. Third node is labeled as2. Connect node2to node2(itself), thus forming a self-cycle.

 

Visually, the graph looks like the following:

       1↵      / ↵     /   ↵    0 --- 2↵         / ↵         \_/↵

 

 

/**
 * Definition for undirected graph.
 * struct UndirectedGraphNode {
 *     int label;
 *     vector neighbors;
 *     UndirectedGraphNode(int x) : label(x) {};
 * };
 */
class Solution {
public:
    std::map mapGraph;
    std::map::iterator iter;
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if(NULL == node) return NULL;
        
        return cloneGFun(node);
}
    UndirectedGraphNode *cloneGFun(UndirectedGraphNode *node){
        iter = mapGraph.end();
        iter = mapGraph.find(node);
        //map中找到了返回second
        if(iter != mapGraph.end()) return iter->second;
        
        //map中找不到执行下面
        UndirectedGraphNode * p;
        p = new UndirectedGraphNode(node->label); 
        mapGraph.insert(std::pair (node,p));
        for(int i=0;i< node->neighbors.size();i++)
            p->neighbors.push_back(cloneGFun(node->neighbors[i]));
        return p;
    }
};

图解leetcode之clone-graph