Given a list of lists in a lexigraphic ordering, return the ordering of the characters in the language.

1) Return a list of all the paths to leaves in the tree. 2) Given a lexicographically sorted list of words, return the order of the alphabet.

Print a linked list in reverse.

Given a linked list with an additional pointer referring to another node in the list, return a deep copy of the list.

1) Find the K nearest points to a vertex. 2) Change your solution under the condition that you have an input file of size 500 Petabytes.

1) Write a square root function. 2) Find the K closest points

1) Write a function to determine the coin closest to you from a list of positions using Manhattan Distance 2) Find the cutoff at which to switch over to a breadth first search algorithm 3) Determine which is the optimal coin to collect when there are opponents present (each opponent only collects one coin)

Given a non-empty array of integers, return the k most frequent elements

1) Write a function to reverse a given string 2) Given an unsorted array of unique integers (size n + 1) and a second array that is identical to the first array but missing one integer (size n), find and output the missing integer