LeetCode: 25. Reverse Nodes in k-Group

Problem: 25. Reverse Nodes in k-Group

Link: https://leetcode.com/problems/reverse-nodes-in-k-group/

Difficulty: Medium

Description:

Given a linked list, reverse the nodes of a linked list k at a time and return its modified list.

k 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 k then left-out nodes in the end should remain as it is.

Example:

Given this linked list: 1->2->3->4->5

For k = 2, you should return: 2->1->4->3->5

For k = 3, you should return: 3->2->1->4->5

Note:

  • Only constant extra memory is allowed.
  • You may not alter the values in the list’s nodes, only nodes itself may be changed.

Solution: 

Language: Swift

Runtime: 48ms
Memory: 19.2MB

Copy to Clipboard