import java.util.*;

/**

* Creator : wts

* Date : 6/26/18

* Title : 133. Clone Graph

* Description :

*

* 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

/ \

\_/

* Analysis :

* the trick is to use hashmap to store the cloned node.

*

*/

class CloneGraphBFS {

public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {

//Set<UndirectedGraphNode> unvistied = new HashSet<>();

if(node == null) return null;

HashMap<Integer, UndirectedGraphNode> visited = new HashMap<>();

Queue<UndirectedGraphNode> q = new LinkedList<>();

q.offer(node);

while(!q.isEmpty()){

int curnum = q.size();

for(int i = 0; i < curnum; i++){

UndirectedGraphNode cur = q.poll();

if(!visited.containsKey(cur.label)){ //

visited.put(cur.label, new UndirectedGraphNode(cur.label));

}

for(UndirectedGraphNode nb : cur.neighbors){

if(!visited.containsKey(nb.label)){ //neighbor not cloned

visited.put(nb.label, new UndirectedGraphNode(nb.label));

visited.get(cur.label).neighbors.add(visited.get(nb.label));

q.offer(nb);

}

else{ //neighbor already cloned

visited.get(cur.label).neighbors.add(visited.get(nb.label));

}

}

}

}

return visited.get(node.label);

}

}

class UndirectedGraphNode {

int label;

List<UndirectedGraphNode> neighbors;

UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }

}

class CloneGraphDFS{

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

public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {

if(node == null) return null;

if(map.containsKey(node.label))

return map.get(node.label);

UndirectedGraphNode nodeclone = new UndirectedGraphNode(node.label);

map.put(node.label, nodeclone);

for(UndirectedGraphNode nb : node.neighbors){

nodeclone.neighbors.add(cloneGraph(nb));

}

return nodeclone;

}

}