<p>给定单链表的头节点 <code>head</code> ，请反转链表，并返回反转后的链表的头节点。</p>

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<p>&nbsp;</p>

<p><strong>示例 1：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/rev1ex1.jpg" style="width: 302px; " />
<pre>
<strong>输入：</strong>head = [1,2,3,4,5]
<strong>输出：</strong>[5,4,3,2,1]
</pre>

<p><strong>示例 2：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/19/rev1ex2.jpg" style="width: 102px;" />
<pre>
<strong>输入：</strong>head = [1,2]
<strong>输出：</strong>[2,1]
</pre>

<p><strong>示例 3：</strong></p>

<pre>
<strong>输入：</strong>head = []
<strong>输出：</strong>[]
</pre>

<p>&nbsp;</p>

<p><strong>提示：</strong></p>

<ul>
	<li>链表中节点的数目范围是 <code>[0, 5000]</code></li>
	<li><code>-5000 &lt;= Node.val &lt;= 5000</code></li>
</ul>

<p>&nbsp;</p>

<p><strong>进阶：</strong>链表可以选用迭代或递归方式完成反转。你能否用两种方法解决这道题？</p>
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<p>&nbsp;</p>

<p><meta charset="UTF-8" />注意：本题与主站 206&nbsp;题相同：&nbsp;<a href="https://leetcode-cn.com/problems/reverse-linked-list/">https://leetcode-cn.com/problems/reverse-linked-list/</a></p>