Project Notes

Reverse Nodes in k-Group

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Description

tab: English
 
<p>Given the <code>head</code> of a linked list, reverse the nodes of the list <code>k</code> at a time, and return <em>the modified list</em>.</p>
 
<p><code>k</code> is a positive integer and is less than or equal to the length of the linked list. If the number of nodes is not a multiple of <code>k</code> then left-out nodes, in the end, should remain as it is.</p>
 
<p>You may not alter the values in the list&#39;s nodes, only nodes themselves may be changed.</p>
 
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/reverse_ex1.jpg" style="width: 542px; height: 222px;" />
<pre>
<strong>Input:</strong> head = [1,2,3,4,5], k = 2
<strong>Output:</strong> [2,1,4,3,5]
</pre>
 
<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/reverse_ex2.jpg" style="width: 542px; height: 222px;" />
<pre>
<strong>Input:</strong> head = [1,2,3,4,5], k = 3
<strong>Output:</strong> [3,2,1,4,5]
</pre>
 
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>
 
<ul>
	<li>The number of nodes in the list is <code>n</code>.</li>
	<li><code>1 &lt;= k &lt;= n &lt;= 5000</code></li>
	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
</ul>
 
<p>&nbsp;</p>
<p><strong>Follow-up:</strong> Can you solve the problem in <code>O(1)</code> extra memory space?</p>
 
 
 
---
 
[submissions](https://leetcode.com/problems/reverse-nodes-in-k-group/submissions/) | [solutions](https://leetcode.com/problems/reverse-nodes-in-k-group/solutions/)
 
 
tab: 中文
 
<p>给你链表的头节点 <code>head</code> ，每&nbsp;<code>k</code><em>&nbsp;</em>个节点一组进行翻转，请你返回修改后的链表。</p>
 
<p><code>k</code> 是一个正整数，它的值小于或等于链表的长度。如果节点总数不是&nbsp;<code>k</code><em>&nbsp;</em>的整数倍，那么请将最后剩余的节点保持原有顺序。</p>
 
<p>你不能只是单纯的改变节点内部的值，而是需要实际进行节点交换。</p>
 
<p>&nbsp;</p>
 
<p><strong>示例 1：</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/reverse_ex1.jpg" style="width: 542px; height: 222px;" />
<pre>
<strong>输入：</strong>head = [1,2,3,4,5], k = 2
<strong>输出：</strong>[2,1,4,3,5]
</pre>
 
<p><strong>示例 2：</strong></p>
 
<p><img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/reverse_ex2.jpg" style="width: 542px; height: 222px;" /></p>
 
<pre>
<strong>输入：</strong>head = [1,2,3,4,5], k = 3
<strong>输出：</strong>[3,2,1,4,5]
</pre>
 
<p>&nbsp;</p>
<strong>提示：</strong>
 
<ul>
	<li>链表中的节点数目为 <code>n</code></li>
	<li><code>1 &lt;= k &lt;= n &lt;= 5000</code></li>
	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
</ul>
 
<p>&nbsp;</p>
 
<p><strong>进阶：</strong>你可以设计一个只用 <code>O(1)</code> 额外内存空间的算法解决此问题吗？</p>
 
<ul>
</ul>
 
 
 
---
 
[提交记录](https://leetcode.cn/problems/reverse-nodes-in-k-group/submissions/) | [题解](https://leetcode.cn/problems/reverse-nodes-in-k-group/solution/)

Solutions & Notes

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