Leetcode 133. 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         / \         \_/

BFS

public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {        if (node == null) return null;                UndirectedGraphNode newNode = new UndirectedGraphNode(node.label);         HashMap<Integer, UndirectedGraphNode> map = new HashMap();                 map.put(newNode.label, newNode);                 LinkedList<UndirectedGraphNode> queue = new LinkedList();         queue.add(node);                 while (!queue.isEmpty()) {             UndirectedGraphNode n = queue.pop();             for (UndirectedGraphNode neighbor : n.neighbors) {                if (!map.containsKey(neighbor.label)) {                     map.put(neighbor.label, new UndirectedGraphNode(neighbor.label));                    queue.add(neighbor);                }                map.get(n.label).neighbors.add(map.get(neighbor.label));             }        }                return newNode;    }

DFS

    Map<Integer, UndirectedGraphNode> map = new HashMap<>();    public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {        return dfs(node);    }        private UndirectedGraphNode dfs(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) {            newNode.neighbors.add(dfs(neighbor));        }        return newNode;    }