# Clone Graph

## Problem

Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

How we serialize an undirected graph:

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 #.

First node is labeled as 0. Connect node 0 to both nodes 1 and 2.

Second node is labeled as 1. Connect node 1 to node 2.

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
/ \
\_/

## Example

return a deep copied graph.

## Code - Java

/**
* Definition for undirected graph.
* class UndirectedGraphNode {
*   int label;
*   ArrayList<UndirectedGraphNode> neighbors;
*   UndirectedGraphNode(int x) {
*     label = x;
*     neighbors = new ArrayList<UndirectedGraphNode>();
*   }
* };
*/
public class Solution {

private Map<Integer, UndirectedGraphNode> map = new HashMap<>();

/**
* @param node: A undirected graph node
* @return: A undirected graph node
*/
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if (node == null) {
return null;
}
if (map.containsKey(node.label)) {
return map.get(node.label);
}
UndirectedGraphNode newNode = new UndirectedGraphNode(node.label);
map.put(node.label, newNode);
for (UndirectedGraphNode neighbor : node.neighbors) {
}