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Description
tab: English
<p>You are given the head of a singly linked-list. The list can be represented as:</p>
<pre>
L<sub>0</sub> → L<sub>1</sub> → … → L<sub>n - 1</sub> → L<sub>n</sub>
</pre>
<p><em>Reorder the list to be on the following form:</em></p>
<pre>
L<sub>0</sub> → L<sub>n</sub> → L<sub>1</sub> → L<sub>n - 1</sub> → L<sub>2</sub> → L<sub>n - 2</sub> → …
</pre>
<p>You may not modify the values in the list's nodes. Only nodes themselves may be changed.</p>
<p> </p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/04/reorder1linked-list.jpg" style="width: 422px; height: 222px;" />
<pre>
<strong>Input:</strong> head = [1,2,3,4]
<strong>Output:</strong> [1,4,2,3]
</pre>
<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/09/reorder2-linked-list.jpg" style="width: 542px; height: 222px;" />
<pre>
<strong>Input:</strong> head = [1,2,3,4,5]
<strong>Output:</strong> [1,5,2,4,3]
</pre>
<p> </p>
<p><strong>Constraints:</strong></p>
<ul>
<li>The number of nodes in the list is in the range <code>[1, 5 * 10<sup>4</sup>]</code>.</li>
<li><code>1 <= Node.val <= 1000</code></li>
</ul>
---
[submissions](https://leetcode.com/problems/reorder-list/submissions/) | [solutions](https://leetcode.com/problems/reorder-list/solutions/)
tab: 中文
<p>给定一个单链表 <code>L</code><em> </em>的头节点 <code>head</code> ，单链表 <code>L</code> 表示为：</p>
<pre>
L<sub>0</sub> → L<sub>1</sub> → … → L<sub>n - 1</sub> → L<sub>n</sub>
</pre>
<p>请将其重新排列后变为：</p>
<pre>
L<sub>0</sub> → L<sub>n</sub> → L<sub>1</sub> → L<sub>n - 1</sub> → L<sub>2</sub> → L<sub>n - 2</sub> → …</pre>
<p>不能只是单纯的改变节点内部的值，而是需要实际的进行节点交换。</p>
<p> </p>
<p><strong>示例 1：</strong></p>
<p><img alt="" src="https://pic.leetcode-cn.com/1626420311-PkUiGI-image.png" style="width: 240px; " /></p>
<pre>
<strong>输入：</strong>head = [1,2,3,4]
<strong>输出：</strong>[1,4,2,3]</pre>
<p><strong>示例 2：</strong></p>
<p><img alt="" src="https://pic.leetcode-cn.com/1626420320-YUiulT-image.png" style="width: 320px; " /></p>
<pre>
<strong>输入：</strong>head = [1,2,3,4,5]
<strong>输出：</strong>[1,5,2,4,3]</pre>
<p> </p>
<p><strong>提示：</strong></p>
<ul>
<li>链表的长度范围为 <code>[1, 5 * 10<sup>4</sup>]</code></li>
<li><code>1 <= node.val <= 1000</code></li>
</ul>
---
[提交记录](https://leetcode.cn/problems/reorder-list/submissions/) | [题解](https://leetcode.cn/problems/reorder-list/solution/)
Solutions & Notes
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