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

Tips:

Code：

``````/**
* 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 node;
}
HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();
ArrayList<UndirectedGraphNode> nodes = bfs(node);
for (UndirectedGraphNode cur : nodes) {
map.put(cur, new UndirectedGraphNode(cur.label));
}
for (UndirectedGraphNode cur: nodes) {
UndirectedGraphNode newNode = map.get(cur);
for (UndirectedGraphNode neighbor : cur.neighbors) {
UndirectedGraphNode newNeighbor = map.get(neighbor);
}
}
return map.get(node);
}
private ArrayList<UndirectedGraphNode> bfs(UndirectedGraphNode node) {
ArrayList<UndirectedGraphNode> result = new ArrayList<>();
HashSet<UndirectedGraphNode> set = new HashSet<UndirectedGraphNode>();
while (!queue.isEmpty()) {
UndirectedGraphNode cur = queue.remove();
for (UndirectedGraphNode neighbor : cur.neighbors) {
if (!set.contains(neighbor)) {
}
}
}
return result;
}
}
``````

`````` private Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
// DFS
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if (node == null) return null;
if (map.containsKey(node)) return map.get(node);
UndirectedGraphNode copy = new UndirectedGraphNode(node.label);
map.put(node, copy);
for (UndirectedGraphNode n : node.neighbors)
return copy;
}

// BFS
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if (node == null) return null;
UndirectedGraphNode copy = new UndirectedGraphNode(node.label);
map.put(node, copy);
while (!q.isEmpty()) {
UndirectedGraphNode cur = q.poll();
for (UndirectedGraphNode neigh : cur.neighbors) {
else {
UndirectedGraphNode neighCopy = new UndirectedGraphNode(neigh.label);
map.put(neigh, neighCopy);