Clone Graph

Clone Graph

 Total Accepted: 4644 TotalSubmissions: 23154My SubmissionsClone an undirected graph. Each node in the graph contains a 

label

 anda list of its 

neighbors

.OJ's undirected graph serialization:Nodes are labeled uniquely.We use 

#

 as a separator for each node, and 

,

 asa 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
/ \
\_/

Discusssolution:Map<原始节点,克隆节点> 储存节点之间的联系，如果一个点在map中有，那么从map中取出，否则新建Node.BFS 遍历 Graph如果此原始节点未被访问过，新建或从map中取节点.遍历原始节点的neighbors, 将neighbors 添加进新节点中.// BFSpublic class CloneGraph {public static UndirectedGraphNode cloneGraph(UndirectedGraphNode node){if(node == null) return null;UndirectedGraphNode root = null;Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>();Set<UndirectedGraphNode> set = new HashSet<>();Queue<UndirectedGraphNode> queue = new LinkedList<>();queue.add(node);while(!queue.isEmpty()){UndirectedGraphNode n = queue.poll();if(set.contains(n)) continue;set.add(n);UndirectedGraphNode cloned = null;if(map.containsKey(n)) cloned = map.get(n);else{cloned = new UndirectedGraphNode(n.label);map.put(n,cloned);}for(UndirectedGraphNode neighbor: n.neighbors){queue.add(neighbor);UndirectedGraphNode clonedNeighbor = null;if(map.containsKey(neighbor)) clonedNeighbor = map.get(neighbor);else{clonedNeighbor = new UndirectedGraphNode(neighbor.label);map.put(neighbor,clonedNeighbor);}cloned.neighbors.add(clonedNeighbor);}if(root == null) root = cloned;}return root;}}

// DFSpublic UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {if(node == null)return null;return clone(node,new HashMap<UndirectedGraphNode, UndirectedGraphNode>(), new HashSet<UndirectedGraphNode>());}private static UndirectedGraphNode clone(UndirectedGraphNode node, Map<UndirectedGraphNode, UndirectedGraphNode> map, Set        <UndirectedGraphNode> visitedSet){if(visitedSet.contains(node))return null;visitedSet.add(node);UndirectedGraphNode clonedNode;if(!map.containsKey(node)){clonedNode = new UndirectedGraphNode(node.label);map.put(node,clonedNode);}else{clonedNode = map.get(node);}for(UndirectedGraphNode n: node.neighbors){if(map.containsKey(n)){clonedNode.neighbors.add(map.970aget(n));}else{UndirectedGraphNode newNode = new UndirectedGraphNode(n.label);clonedNode.neighbors.add(newNode);map.put(n,newNode);}clone(n,map,visitedSet);}return clonedNode;}