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Description
tab: English
<p>Given the <code>head</code> of a singly linked list, return <code>true</code><em> if it is a </em><span data-keyword="palindrome-sequence"><em>palindrome</em></span><em> or </em><code>false</code><em> otherwise</em>.</p>
<p> </p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/pal1linked-list.jpg" style="width: 422px; height: 62px;" />
<pre>
<strong>Input:</strong> head = [1,2,2,1]
<strong>Output:</strong> true
</pre>
<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/pal2linked-list.jpg" style="width: 182px; height: 62px;" />
<pre>
<strong>Input:</strong> head = [1,2]
<strong>Output:</strong> false
</pre>
<p> </p>
<p><strong>Constraints:</strong></p>
<ul>
<li>The number of nodes in the list is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
<li><code>0 <= Node.val <= 9</code></li>
</ul>
<p> </p>
<strong>Follow up:</strong> Could you do it in <code>O(n)</code> time and <code>O(1)</code> space?
---
[submissions](https://leetcode.com/problems/palindrome-linked-list/submissions/) | [solutions](https://leetcode.com/problems/palindrome-linked-list/solutions/)
tab: 中文
<p>给你一个单链表的头节点 <code>head</code> ，请你判断该链表是否为<span data-keyword="palindrome-sequence">回文链表</span>。如果是，返回 <code>true</code> ；否则，返回 <code>false</code> 。</p>
<p> </p>
<p><strong>示例 1：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/pal1linked-list.jpg" style="width: 422px; height: 62px;" />
<pre>
<strong>输入：</strong>head = [1,2,2,1]
<strong>输出：</strong>true
</pre>
<p><strong>示例 2：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/03/pal2linked-list.jpg" style="width: 182px; height: 62px;" />
<pre>
<strong>输入：</strong>head = [1,2]
<strong>输出：</strong>false
</pre>
<p> </p>
<p><strong>提示：</strong></p>
<ul>
<li>链表中节点数目在范围<code>[1, 10<sup>5</sup>]</code> 内</li>
<li><code>0 <= Node.val <= 9</code></li>
</ul>
<p> </p>
<p><strong>进阶：</strong>你能否用 <code>O(n)</code> 时间复杂度和 <code>O(1)</code> 空间复杂度解决此题？</p>
---
[提交记录](https://leetcode.cn/problems/palindrome-linked-list/submissions/) | [题解](https://leetcode.cn/problems/palindrome-linked-list/solution/)
Solutions & Notes
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