"""
# Definition for a Node.
class Node:
    def __init__(self, val = 0, neighbors = None):
        self.val = val
        self.neighbors = neighbors if neighbors is not None else []
"""

class Solution:
    def cloneGraph(self, node: 'Node') -> 'Node':

        # keep track of cloned nodes
        hashmap = {}

        def dfs(node):
            if node in hashmap:
                return hashmap[node]

            cloned_node = Node(node.val)
            hashmap[node] = cloned_node

            # creating a new list called neighbors
            # and appending to that list and later saying
            # cloned_node.neighbors = neighbours
            # gave me a memory limit exceeded error
            for neighbour in node.neighbors:
                cloned_node.neighbors.append(
                    dfs(neighbour)
                )

            hashmap[node] = cloned_node

            return cloned_node

        return dfs(node) if node else None