swap-nodes-in-pairs

java

python

python3

mysql

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oraclesql

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swift

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Algorithms

Given a&nbsp;linked list, swap every two adjacent nodes and return its head. You must solve the problem without&nbsp;modifying the values in the list&#39;s nodes (i.e., only nodes themselves may be changed.)

&nbsp;
Example 1:

<div class="example-block">
Input: head = [1,2,3,4]

Output: [2,1,4,3]

Explanation:

<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/swap_ex1.jpg" style="width: 422px; height: 222px;" />
</div>

Example 2:

<div class="example-block">
Input: head = []

Output: []
</div>

Example 3:

<div class="example-block">
Input: head = [1]

Output: [1]
</div>

Example 4:

<div class="example-block">
Input: head = [1,2,3]

Output: [2,1,3]
</div>

&nbsp;
Constraints:

<ul>
	<li>The number of nodes in the&nbsp;list&nbsp;is in the range <code>[0, 100]</code>.</li>
	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
</ul>

swapPairs

Swap Nodes in Pairs

Reverse Nodes in k-Group

reverse-nodes-in-k-group

K 个一组翻转链表

Swapping Nodes in a Linked List

swapping-nodes-in-a-linked-list

交换链表中的节点

Recursion

Linked List

给你一个链表，两两交换其中相邻的节点，并返回交换后链表的头节点。你必须在不修改节点内部的值的情况下完成本题（即，只能进行节点交换）。

&nbsp;

示例 1：
<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/swap_ex1.jpg" style="width: 422px; height: 222px;" />
<pre>
输入：head = [1,2,3,4]
输出：[2,1,4,3]
</pre>

示例 2：

<pre>
输入：head = []
输出：[]
</pre>

示例 3：

<pre>
输入：head = [1]
输出：[1]
</pre>

&nbsp;

提示：

<ul>
	<li>链表中节点的数目在范围 <code>[0, 100]</code> 内</li>
	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
</ul>