Given a reference of a node in a connected undirected graph.
\n\nReturn a deep copy (clone) of the graph.
\n\nEach node in the graph contains a value (int) and a list (List[Node]) of its neighbors.
\nclass Node {\n public int val;\n public List<Node> neighbors;\n}\n\n\n\n\n
Test case format:
\n\nFor simplicity, 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.
An 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.
\n\nThe 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.
\n
Example 1:
\n![\"\"](\"https://assets.leetcode.com/uploads/2019/11/04/133_clone_graph_question.png\")
\n\nInput: adjList = [[2,4],[1,3],[2,4],[1,3]]\nOutput: [[2,4],[1,3],[2,4],[1,3]]\nExplanation: There are 4 nodes in the graph.\n1st node (val = 1)'s neighbors are 2nd node (val = 2) and 4th node (val = 4).\n2nd node (val = 2)'s neighbors are 1st node (val = 1) and 3rd node (val = 3).\n3rd node (val = 3)'s neighbors are 2nd node (val = 2) and 4th node (val = 4).\n4th node (val = 4)'s neighbors are 1st node (val = 1) and 3rd node (val = 3).\n\n\n
Example 2:
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/01/07/graph.png\")
\n\nInput: adjList = [[]]\nOutput: [[]]\nExplanation: 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.\n\n\n
Example 3:
\n\n\nInput: adjList = []\nOutput: []\nExplanation: This an empty graph, it does not have any nodes.\n\n\n
\n
Constraints:
\n\n[0, 100].1 <= Node.val <= 100Node.val is unique for each node.Compiled with clang 11 using the latest C++ 20 standard.
Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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