leetcode [Clone Graph] Java

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 node0 to both nodes 1 and2.
2. Second node is labeled as 1. Connect node1 to node 2.
3. Third node is labeled as 2. Connect node2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

题意很简单，就是深度复制，我选择了直接new。

至于遍历，在这个DFS比BFS方便，直接递归就可以了。

记录的话用了HashMap，注意还要储存node的值。

/** * Definition for undirected graph. * class UndirectedGraphNode { *     int label; *     List<UndirectedGraphNode> neighbors; *     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); } * }; */import java.util.HashMap;public class Solution {    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {        HashMap<Integer, UndirectedGraphNode> record = new HashMap<Integer, UndirectedGraphNode>();        return clone(node, record);    }    private UndirectedGraphNode clone(UndirectedGraphNode node, HashMap<Integer, UndirectedGraphNode> record) {        if(node == null) return node;        if(record.containsKey(node.label)) return record.get(node.label);        UndirectedGraphNode snode = new UndirectedGraphNode(node.label);        record.put(node.label, snode);        for (UndirectedGraphNode dnode : node.neighbors) {            snode.neighbors.add(clone(dnode, record));        }        return snode;    }}