LeetCode: Clone Graph

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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         /          \_/
地址：https://oj.leetcode.com/problems/clone-graph/
演算法：把整個圖複製下來，基本就是利用map來完成的，複製的過程採用遞迴完成。代碼：

 1 /** 2  * Definition for undirected graph. 3  * struct UndirectedGraphNode { 4  *     int label; 5  *     vector<UndirectedGraphNode *> neighbors; 6  *     UndirectedGraphNode(int x) : label(x) {}; 7  * }; 8  */ 9 class Solution {10 public:11     UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {12         if(!node){13             return NULL;14         }15         map<int,UndirectedGraphNode *> hash_table;16         set<int> isTraved;17         return subClone(node,hash_table,isTraved);18     }19     UndirectedGraphNode *subClone(UndirectedGraphNode *node, map<int,UndirectedGraphNode*> &hash_table, set<int> &isTraved){20         if(!node){21             return NULL;22         }23         int label = node->label;24         if(isTraved.find(label) != isTraved.end()){25             return hash_table[label];26         }27         if(hash_table.find(label) == hash_table.end()){28             hash_table[label] = new UndirectedGraphNode(label);29         }30         isTraved.insert(label);31         UndirectedGraphNode *p = hash_table[label];32         vector<UndirectedGraphNode *>::iterator it = node->neighbors.begin();33         for(; it != node->neighbors.end(); ++it){34             p->neighbors.push_back(subClone(*it,hash_table,isTraved));35         }36         return p;37     }38 };

 

 

LeetCode: Clone Graph