25. Reverse Nodes in k-Group
Hard
50 Points
Linked List
Recursion
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 left-out nodes, in the end, should remain as it is.
You may not alter the values in the list's nodes, only nodes themselves may be changed.
Examples
Example 1
Input: head = [1,2,3,4,5], k = 2
Output: [2,1,4,3,5]
Example 2
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 <= 50000 <= Node.val <= 1000
25. Reverse Nodes in k-Group
Hard
50 Points
Linked List
Recursion
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 left-out nodes, in the end, should remain as it is.
You may not alter the values in the list's nodes, only nodes themselves may be changed.
Examples
Example 1
Input: head = [1,2,3,4,5], k = 2
Output: [2,1,4,3,5]
Example 2
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 <= 50000 <= Node.val <= 1000