# Clone Graph

Clone Graph first search

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 #.

``````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
//          / \
//          \_/
``````

Clone Graph Solution

``````/**
* Definition for undirected graph.
* class UndirectedGraphNode {
*     int label;
*     List<UndirectedGraphNode> neighbors;
*     UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
* };
*/
public class CloneGraph {
public HashMap<Integer, UndirectedGraphNode> map = new HashMap<Integer, UndirectedGraphNode>();

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(newNode.label, newNode);

for(UndirectedGraphNode neighbor : node.neighbors) {