[leetcode]Clone Graph

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         / \         \_/

题意：克隆无向图，每个结点有标签和邻居属性组成

解题思路：BFS 使用队列实现，并用map记录访问过的结点

/** * Definition for undirected graph. * class UndirectedGraphNode { *     int label; *     List<UndirectedGraphNode> neighbors; *     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); } * }; */public class Solution {    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {        if(node == null) return null;        UndirectedGraphNode retNode = new UndirectedGraphNode(node.label);                Queue<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>();        queue.add(node);        Queue<UndirectedGraphNode> destQueue = new LinkedList<UndirectedGraphNode>();        destQueue.add(retNode);                Map<Integer, UndirectedGraphNode> destMap = new HashMap<Integer, UndirectedGraphNode>();        destMap.put(retNode.label, retNode);        while(!destQueue.isEmpty()){            UndirectedGraphNode srcNode = queue.remove();            List<UndirectedGraphNode> srcList = srcNode.neighbors;                        UndirectedGraphNode destNode = destQueue.remove();            List<UndirectedGraphNode> destList = destNode.neighbors;                         //更新克隆图的邻居            for(int i = 0; i < srcList.size(); i++){                Integer destKey = srcList.get(i).label;                UndirectedGraphNode dNode = destMap.get(destKey);                if(dNode == null){                    dNode = new UndirectedGraphNode(destKey);                    destMap.put(dNode.label, dNode);                    destQueue.add(dNode);                    queue.add(srcList.get(i));                }                destList.add(dNode);            }        }                return retNode;    }}