Reverse Nodes in k-Group

HardLinked ListsLinked List

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

Given the head of a linked list, reverse the nodes of the list k at a time, and return the 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 the remaining nodes at the end should be left as-is. You may not alter the values in the list's nodes, only the nodes themselves may be changed.

Examples

Input: head = [1,2,3,4,5], k = 2
Output: [2,1,4,3,5]
Input: head = [1,2,3,4,5], k = 3
Output: [3,2,1,4,5]

Constraints

  • The number of nodes in the list is n.
  • 1 <= k <= n <= 5000
  • 0 <= Node.val <= 1000

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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