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, group all the nodes with odd indices together followed by the nodes with even indices, and return the reordered 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 are given the root of a binary tree with n nodes, where each node is uniquely assigned a value from 1 to n.

Given a non-empty string containing an out-of-order English representation of digits 0-9, output the digits in ascending order.

Given a string, your task is to count how many palindromic substrings in this string.

We are given two arrays A and B of words. Each word is a string of lowercase letters.

Given an m x n matrix of non-negative integers representing the height of each unit cell in a continent,