LeetCode Graph：M133_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         / \         \_/

package com.graph;import java.util.*;//Definition for undirected graph.class UndirectedGraphNode {    int label;    List<UndirectedGraphNode> neighbors;    UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }};public class M133_Clone_Graph {    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {        Queue<UndirectedGraphNode> Q = new LinkedList<UndirectedGraphNode>();        Map<Integer, UndirectedGraphNode> map = new HashMap<Integer, UndirectedGraphNode>();                        if(node == null)        return null;                Q.add(node);        UndirectedGraphNode newNode = new UndirectedGraphNode(node.label);        map.put(newNode.label, newNode);        while(!Q.isEmpty()) {        UndirectedGraphNode t = Q.poll();        UndirectedGraphNode tt = map.get(t.label);        for(UndirectedGraphNode adj:t.neighbors) {        UndirectedGraphNode newAdj = null;        if(map.containsKey(adj.label)) {        newAdj = map.get(adj.label);        }else {        newAdj = new UndirectedGraphNode(adj.label);        map.put(newAdj.label, newAdj);        //Revise        Q.add(adj);        }        tt.neighbors.add(newAdj);             //Error        //Q.add(adj);        }        }                return newNode;    }}