Grokking the Coding Interview: Patterns for Coding Questions
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Problem Challenge 1: Reverse alternating K-element Sub-list (medium)

Problem Statement

Given the head of a LinkedList and a number ‘k’, reverse every alternating ‘k’ sized sub-list starting from the head.

If, in the end, you are left with a sub-list with less than ‘k’ elements, reverse it too.


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

Try it yourself

Try solving this question here:




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