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"content": "<p>Given a reference of a node in a <strong><a href=\"https://en.wikipedia.org/wiki/Connectivity_(graph_theory)#Connected_graph\" target=\"_blank\">connected</a></strong> undirected graph.</p>\n\n<p>Return a <a href=\"https://en.wikipedia.org/wiki/Object_copying#Deep_copy\" target=\"_blank\"><strong>deep copy</strong></a> (clone) of the graph.</p>\n\n<p>Each node in the graph contains a value (<code>int</code>) and a list (<code>List[Node]</code>) of its neighbors.</p>\n\n<pre>\nclass Node {\n public int val;\n public List<Node> neighbors;\n}\n</pre>\n\n<p> </p>\n\n<p><strong>Test case format:</strong></p>\n\n<p>For simplicity, each node's value is the same as the node's index (1-indexed). For example, the first node with <code>val == 1</code>, the second node with <code>val == 2</code>, and so on. The graph is represented in the test case using an adjacency list.</p>\n\n<p><b>An adjacency list</b> is a collection of unordered <b>lists</b> used to represent a finite graph. Each list describes the set of neighbors of a node in the graph.</p>\n\n<p>The given node will always be the first node with <code>val = 1</code>. You must return the <strong>copy of the given node</strong> as a reference to the cloned graph.</p>\n\n<p> </p>\n<p><strong>Example 1:</strong></p>\n<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2019/11/04/133_clone_graph_question.png\" style=\"width: 454px; height: 500px;\" />\n<pre>\n<strong>Input:</strong> adjList = [[2,4],[1,3],[2,4],[1,3]]\n<strong>Output:</strong> [[2,4],[1,3],[2,4],[1,3]]\n<strong>Explanation:</strong> 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</pre>\n\n<p><strong>Example 2:</strong></p>\n<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2020/01/07/graph.png\" style=\"width: 163px; height: 148px;\" />\n<pre>\n<strong>Input:</strong> adjList = [[]]\n<strong>Output:</strong> [[]]\n<strong>Explanation:</strong> 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</pre>\n\n<p><strong>Example 3:</strong></p>\n\n<pre>\n<strong>Input:</strong> adjList = []\n<strong>Output:</strong> []\n<strong>Explanation:</strong> This an empty graph, it does not have any nodes.\n</pre>\n\n<p> </p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li>The number of nodes in the graph is in the range <code>[0, 100]</code>.</li>\n\t<li><code>1 <= Node.val <= 100</code></li>\n\t<li><code>Node.val</code> is unique for each node.</li>\n\t<li>There are no repeated edges and no self-loops in the graph.</li>\n\t<li>The Graph is connected and all nodes can be visited starting from the given node.</li>\n</ul>\n",
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For the latest Python, please choose Python3 instead.</p>\"], \"c\": [\"C\", \"<p>Compiled with <code>gcc 8.2</code> using the gnu99 standard.</p>\\r\\n\\r\\n<p>Your code is compiled with level one optimization (<code>-O1</code>). <a href=\\\"https://github.com/google/sanitizers/wiki/AddressSanitizer\\\" target=\\\"_blank\\\">AddressSanitizer</a> is also enabled to help detect out-of-bounds and use-after-free bugs.</p>\\r\\n\\r\\n<p>Most standard library headers are already included automatically for your convenience.</p>\\r\\n\\r\\n<p>For hash table operations, you may use <a href=\\\"https://troydhanson.github.io/uthash/\\\" target=\\\"_blank\\\">uthash</a>. \\\"uthash.h\\\" is included by default. Below are some examples:</p>\\r\\n\\r\\n<p><b>1. 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