133. Clone Graph(图的复制)


Given the head of a graph, return a deep copy (clone) of the graph. Each node in the graph contains a label (int) and a list (List[UndirectedGraphNode]) of its neighbors. There is an edge between the given node and each of the nodes in its neighbors.


OJ's undirected graph serialization (so you can understand error output):

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
         / \
         \_/

Note: The information about the tree serialization is only meant so that you can understand error output if you get a wrong answer. You don't need to understand the serialization to solve the problem.

 

 

 

DFS

 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==NULL) return NULL;
13         if (mp.find(node->label) == mp.end()){ 
14         mp[node->label] = new UndirectedGraphNode(node -> label);
15         for (UndirectedGraphNode* neigh : node -> neighbors)
16              mp[node->label] -> neighbors.push_back(cloneGraph(neigh));
17         }
18         return mp[node->label];
19         
20     }
21 private:
22     unordered_map<int, UndirectedGraphNode*> mp;
23 };

 

 

posted @ 2019-01-17 21:04  乐乐章  阅读(147)  评论(0)    收藏  举报