LeetCode133——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 #.

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:

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

难度系数：

中等

实现

class Solution {
unordered_map<UndirectedGraphNode*, UndirectedGraphNode*> hash;
public:
    UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
        if (!node) return nullptr;
        if (hash.find(node) == hash.end()) {
            hash[node] = new UndirectedGraphNode(node->label);
            for (auto n : node->neighbors) {
                hash[node]->neighbors.push_back(cloneGraph(n));
            }
        }
        return hash[node];
    }
};