leetcode - Clone Graph_neighbors[i].map-优快云博客

本文链接：https://blog.youkuaiyun.com/AkibaTakuya/article/details/39611017

本文介绍了一种基于深度优先搜索(DFS)的无向图克隆算法，该算法能够有效地复制图中每个节点及其邻居关系，并通过使用哈希表来避免重复克隆相同节点。

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 #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
Second node is labeled as 1. Connect node 1 to node 2.
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:

/**
 * Definition for undirected graph.
 * struct UndirectedGraphNode {
 *     int label;
 *     vector<UndirectedGraphNode *> neighbors;
 *     UndirectedGraphNode(int x) : label(x) {};
 * };
 */
struct UndirectedGraphNode
{
	int label;
	std::vector<UndirectedGraphNode *> neighbors;
	UndirectedGraphNode(int x) : label(x) {};
};
class Solution {
public:
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
		std::unordered_map<UndirectedGraphNode*, UndirectedGraphNode *> map;
        if(node == NULL) return node;
		return dfs(node,map);
    }
private:
	UndirectedGraphNode *dfs(UndirectedGraphNode *node,std::unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> &map)
	{
		if(map.count(node) > 0) return map[node];
		UndirectedGraphNode *newNode = new UndirectedGraphNode(node->label);
		map[node] = newNode;
		for(int i = 0; i < node->neighbors.size(); i++)
		{
			newNode->neighbors.push_back(dfs(node->neighbors[i],map));
		}
		return newNode;
	}
};