https://leetcode.com/problems/clone-graph/
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.
class Node { public int val; public List neighbors; }
Test case format:
For simplicity sake, each node's value is the same as the node's index (1-indexed).
For example, the first node with val = 1, the second node with val = 2, and so on.
The graph is represented in the test case using an adjacency list.
Adjacency list is a collection of unordered lists used to represent a finite graph.
Each list describes the set of neighbors of a node in the graph.
The given node will always be the first node with val = 1.
You must return the copy of the given node as a reference to the cloned graph.
Example 1:
Input: adjList = [[2,4],[1,3],[2,4],[1,3]] Output: [[2,4],[1,3],[2,4],[1,3]] Explanation: There are 4 nodes in the graph. 1st node (val = 1)'s neighbors are 2nd node (val = 2) and 4th node (val = 4). 2nd node (val = 2)'s neighbors are 1st node (val = 1) and 3rd node (val = 3). 3rd node (val = 3)'s neighbors are 2nd node (val = 2) and 4th node (val = 4). 4th node (val = 4)'s neighbors are 1st node (val = 1) and 3rd node (val = 3). Example 2:
1
Input: adjList = [[]] Output: [[]] Explanation: Note that the input contains one empty list. The graph consists of only one node with val = 1 and it does not have any neighbors. Example 3:
Input: adjList = [] Output: [] Explanation: This an empty graph, it does not have any nodes. Example 4:
1--2
Input: adjList = [[2],[1]] Output: [[2],[1]]
Constraints:
1 <= Node.val <= 100 Node.val is unique for each node. Number of Nodes will not exceed 100. There is no repeated edges and no self-loops in the graph. The Graph is connected and all nodes can be visited starting from the given node.