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
         / \
         \_/

 

直接用HashMap来做应该是最简单的，这个对十字链表也可以。使用hashmap来存储node的对应关系。

 1 /**
 2  * Definition for undirected graph.
 3  * class UndirectedGraphNode {
 4  *     int label;
 5  *     ArrayList<UndirectedGraphNode> neighbors;
 6  *     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
 7  * };
 8  */
 9 public class Solution {
10     HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
11     public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
12         map.clear();
13         return cloneNode(node);
14     }
15      
16     private UndirectedGraphNode cloneNode(UndirectedGraphNode node)
17     {
18         if (node == null) return null;
19         if (map.containsKey(node)) return map.get(node);
20         else
21         {
22             UndirectedGraphNode copy = new UndirectedGraphNode(node.label);
23             map.put(node, copy);
24             for (UndirectedGraphNode n : node.neighbors)
25             {
26                 copy.neighbors.add(cloneNode(n));
27             }
28             return copy;
29         }
30     }
31 }

 

 

 

posted on 2013-10-18 07:57  Step-BY-Step  阅读(170)  评论(0)  编辑  收藏  举报

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