You are given a doubly linked list which in addition to the next and previous pointers, it could have a child pointer, which may or may not point

A linked list of length n is given such that each node contains an additional random pointer, which could point to any node in the list, or null.

Given the head of a singly linked list, return true if it is a palindrome.

Given the head of a singly linked list, group all the nodes with odd indices together followed by the nodes with even indices, and return the reordered list.

Merge two sorted linked lists and return it as a sorted list. The list should be made by splicing together the nodes of the first two lists.

Given the head of a linked list and an integer val, remove all the nodes of the linked list that has Node.val == val, and return the new head.

Given the head of a singly linked list, reverse the list, and return the reversed list.

Given the head of a linked list, rotate the list to the right by k places.

You are given two non-empty linked lists representing two non-negative integers.

You want to form a target string of lowercase letters.