Write a program to reverse a singly linked list? Modify that program to reverse a doubly linked list.

Write a function to efficiently determine if a linked list has a cycle in it.

Write a function that takes as input a sorted array and modifies the array to compact it, removing duplicates. Also return the new length of the array.

Notes: The input array might be very large.

For example:

• input array = [1, 3, 7, 7, 8, 9, 9, 9, 10]
• transformed array = [1, 3, 7, 8, 9, 10]
• size = 6

Given two arrays of strings, A and B.

B contains every element in A, and has one additional member, for example:

* A = ['dog', 'cat', 'monkey]
* B = ['cat', 'rat', 'dog', 'monkey']

Write a function to find the extra string in B. Do this in O(n)

Express the following table as a static structure, and write a function, find_routes(source, destination) that efficiently outputs all possible routes.

Source  | Dest
~~~~~~    ~~~~
Seattle | LA
LA      | Florida
LA      | Maine
Florida | Seattle
Seattle | Florida

The solution for find_routes('Seattle', 'Florida') should be [Seattle -> Florida, Seattle -> LA -> Florida]

Write a function to efficiently convert a floating point number to a rational number. For example, given 0.125 return "1/8"