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
         / 
         \_/

题目意思是克隆一张图。

我的解题思路是 先用bfs遍历原来的图，把label和节点加入到map中。

然后新建一个复制节点的map，遍历原来map，第一遍遍历新建节点 加入到新map中，第二遍把邻节点list加到新节点中。

/**
 * Definition for undirected graph.
 * class UndirectedGraphNode {
 *     int label;
 *     List<UndirectedGraphNode> neighbors;
 *     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
 * };
 */
public class Solution {
    private void     bfs(UndirectedGraphNode node,HashMap<Integer, UndirectedGraphNode> visitedmap) {
        
        LinkedList<UndirectedGraphNode> tovisitList = new LinkedList<>();
        
        tovisitList.addLast(node);
        while (!tovisitList.isEmpty()) {
            UndirectedGraphNode first = tovisitList.getFirst();
            tovisitList.removeFirst();
            visitedmap.put(first.label, first);
            for (UndirectedGraphNode undirectedGraphNode : first.neighbors) {
                if (!visitedmap.containsKey(undirectedGraphNode.label)&&!tovisitList.contains(undirectedGraphNode)) {
                    tovisitList.addLast(undirectedGraphNode);
                }
            }
        }
        
    }
    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
        if (node==null) {
            return null;
        }
        UndirectedGraphNode newGraph = new UndirectedGraphNode(node.label);
        if (node.neighbors.isEmpty()) {
            return newGraph;
        }
        HashMap<Integer, UndirectedGraphNode> visitedmap=new HashMap<>();
        HashMap<Integer, UndirectedGraphNode> copymap=new HashMap<>();
        bfs(node, visitedmap);
        for (Integer key : visitedmap.keySet()) {
            copymap.put(key, new UndirectedGraphNode(key));
        }
        for (Integer key : visitedmap.keySet()) {
            for (UndirectedGraphNode tnode : visitedmap.get(key).neighbors) {
                copymap.get(key).neighbors.add(copymap.get(tnode.label));
            }
        }
        return copymap.get(node.label);
        
    }
    

}