[leetcode]133. Clone Graph 克隆图

题目

给定一个无向图的节点，克隆能克隆的一切

思路

1--2
|
3--5

以上图为例，

node neighbor

1 2， 3

2 1

3 1， 5

5 3

首先从1开始, 将（node，newNode）put到HashMap中

node newNode

1 1

然后遍历该node的所有neighbor

node neighbor

1 2， 3

此时遍历到2

将（node，newNode）put到HashMap中

node newNode

1 1 -- 2 // newNode.neighbors.add(clone)

2 2

代码

 1 public class Solution {
 2     
 3     Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();
 4     
 5     public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
 6         if (node == null) {
 7             return null;
 8         }
 9         
10         //DFS
11         if (map.containsKey(node)) {
12             return map.get(node);
13         }
14         
15         UndirectedGraphNode newNode = new UndirectedGraphNode(node.label);
16         map.put(node, newNode);
17         for (UndirectedGraphNode nei : node.neighbors) {
18             UndirectedGraphNode clone = cloneGraph(nei);
19             newNode.neighbors.add(clone);
20         }
21         return newNode;
22     }       
23 }