problem24

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24. Swap Nodes in Pairs (Medium)

Given a linked list, swap every two adjacent nodes and return its head.

 

Example 1:

Input: head = [1,2,3,4]
Output: [2,1,4,3]

Example 2:

Input: head = []
Output: []

Example 3:

Input: head = [1]
Output: [1]

 

Constraints:

• The number of nodes in the list is in the range [0, 100].
• 0 <= Node.val <= 100

 

Follow up: Can you solve the problem without modifying the values in the list's nodes? (i.e., Only nodes themselves may be changed.)

Related Topics

[Recursion] [Linked List]

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