Given a reference of a node in a connected undirected graph, return a deep copy (clone) of the graph. Each node in the graph contains a val (int) and a list (List[Node]) of its neighbors.
Explanation: Node 1’s value is 1, and it has two neighbors: Node 2 and 4. Node 2’s value is 2, and it has two neighbors: Node 1 and 3. Node 3’s value is 3, and it has two neighbors: Node 2 and 4. Node 4’s value is 4, and it has two neighbors: Node 1 and 3.
Note
The number of nodes will be between 1 and 100.
The undirected graph is a simple graph, which means no repeated edges and no self-loops in the graph.
Since the graph is undirected, if node p has node q as neighbor, then node q must have node p as neighbor too.
You must return the copy of the given node as a reference to the cloned graph.
O(n) runtime, O(n) space – Depth-first traversal
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publicclass{ int label; List<UndirectedGraphNode> neighbors; UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); } }
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node){ if (node == null) returnnull;
Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<>(); return bfs(map, node); }
private UndirectedGraphNode bfs(Map<UndirectedGraphNode, UndirectedGraphNode> map, UndirectedGraphNode node){ Queue<UndirectedGraphNode> queue = new LinkedList<>(); UndirectedGraphNode copy = new UndirectedGraphNode(node.label); map.put(node, copy); queue.offer(node);
while (!queue.isEmpty()) { UndirectedGraphNode current = queue.poll();
for (UndirectedGraphNode neighbor : current.neighbors) { if (!map.containsKey(neighbor)) { queue.offer(neighbor); map.put(neighbor, new UndirectedGraphNode(neighbor.label)); }
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