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

Suppose I have the following Array of tuples

[ ['a',1], ['b',2], ['c','3' ]

How can I convert this to a Hash?

{ 'a' => 1, 'b' => 2, 'c' => 3}

Once I've written the algorithm, how would I make it generally available throughout my Ruby application?

Use Newton's method to approximate the square root of a method. Newton's method is to approximate z = Sqrt(x) by picking a starting point z and then repeating:

z = z - (z*z - x)/(2*z)

Pick a sensible point to stop the iteration.

Most languages have a built in sort method that will sort an array of strings alphabetically. Demonstrate how to sort an array of strings by the length of each string, shortest strings first.

Assume that you have access to an employee's email Inbox, and that you can parse the content of their emails, including the email headers.

1. How can you use this to deduce their first-degree connections?
2. What kind of heuristics can you come up with to quantify the strength of these first-degree connections?
3. How can you use this to deduce their second-degree connections?
4. How can you use this to deduce their third-degree connections?

Suppose you have an array of 99 numbers. The array contains the digits 1 to 100 with one digit missing. Describe four different algorithms to compute the missing number. Two of these should optimize for low storage and two of these should optimize for fast processing.

Write a string to find a substring in a given string. Do this in O(n) or better

Write an iterative function to reverse a string. Do the same thing as a recursive function.

Write a function to implement strstr() i.e. find the first occurrence of one string inside another string.

Write a program to print out a multiplication table, from 1x1 to 12x12. This should look like:

   1   2   3   4   5   6   7   8   9  10  11  12
   2   4   6   8  10  12  14  16  18  20  22  24
   3   6   9  12  15  18  21  24  27  30  33  36
   4   8  12  16  20  24  28  32  36  40  44  48
   5  10  15  20  25  30  35  40  45  50  55  60
   6  12  18  24  30  36  42  48  54  60  66  72
   7  14  21  28  35  42  49  56  63  70  77  84
   8  16  24  32  40  48  56  64  72  80  88  96
   9  18  27  36  45  54  63  72  81  90  99 108
  10  20  30  40  50  60  70  80  90 100 110 120
  11  22  33  44  55  66  77  88  99 110 121 132
  12  24  36  48  60  72  84  96 108 120 132 144

Explain big o notation and how it is useful in computer science to classify algorithms.

• What order is a hash table lookup?
• What order is determining if a number is even or odd?
• What order is finding an item in an unsorted list?
• What order is a binary search?

Describe bitwise operators AND, OR, XOR and NOT. Describe how you might use these.

How do these bitwise operators differ from logical operators?

Write a program to find the largest integer in an array of integers.

Write a function that sums up integers from a text file that looks like the following:

1
3
27
2
2123

Write function to print the odd numbers from 1 to 99

Can an inner class be defined inside a method? What variables can be accessed by that class?

Write a python program that will take the following list of words as input and output a dictionary with a the frequency of each word:

words = ['apple', 'apple', 'banana', 'banana', 'banana', 'pear', 'banana', 'pear', 'pear', 'pear', 'pear', 'pear']

Describe consistent hashing and the advantages that it has over traditional hashing techniques. How can this technique help while scaling distributed systems, for example, distributed hash tables?

Replace the string The quick brown fox jumps over the lazy dog with the string The1 quick2 brown3 fox4 jumps5 over6 the7 lazy8 dog9.

If you have access to a function that returns a random integer from one to five, write another function which returns a random integer from one to seven.

Discuss an algorithm to traverse a tree, depth first.

Implement a function with signature find_chars(string1, string2) that takes two strings and returns a string that contains only the characters found in string1 and string two in the order that they are found in string1. Implement a version of order N*N and one of order N.

Given a N by N matrix of both negative and positive integers. Write an efficient algorithm to find the sub-matrix with the largest sum of all the contained elements.

Implement a function to divide two integers without using the divide operator.

Design a system to efficiently calculate the top 1MM Google search queries and create a report of these. Additionally:

• You are given twelve servers
• Each has two processors, 4GB of ram and four 400GB hard drives.
• The machines are networked
• The log data as roughly 100 Billion log lines in it.
• The log data comes in twelve, 320 Gb files.
• Each line of the files has roughly 40 search queries
• You can only use open source software or software that you write.

Given an array A[N] containing N numbers. Crate an array Output[N] where Output[i] is equal to the product of all the elements of A[N] except A[i].

For example Output[0] is the product of A[1] to A[N-1] and Output[1] is the product of A[0] and from A[2] to A[N-1].

Do this without using the division operator. Do it in O(n).

You are given a linked list of integers of length N.

N is very large and you don’t know N.

Write a function to return k completely random numbers from the list.

Do this in O(n).

Hint: Use random function rand() (returns a number between 0 and 1) and irand() (return either 0 or 1) 2.

Write a function to efficiently determine the result of a game of Tic Tac Toe.

The function takes as input the game and the sign (x or o) of the player. The function returns if this player has won the game or not.

Carefully consider both the data structure and the algorithm for your answer.

Efficiently calculate the shortest distance between two Facebook users given an API endpoint that returns all friends of a given user.

Given any integer, efficiently find the next highest integer that uses the same digits.

For example if the number is 15432, you should return 21345.

Write a function that takes an integer and returns the smallest number that is greater than the given number which is a palendrome.

For example, if the input was 111 the next palindromic number would be 121.

Write a function that, given a word and a dictionary will efficiently return the minimal edits (character addition or deletion) to get to a word that exists in the dictionary.

Write a function, tokenize_string(input_string, delimiter_list) that returns a list of strings that are separated by the delimiters.

For example: tokenize_string("How now, Mrs. Brown Cow") returns ['How', 'now', 'Mrs', 'Brown', 'Cow']

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)

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

Write a function that takes an unsorted integer array, and returns a three element subset whose sum is zero.

Note: This is a special case of the SUBSET-SUM problem. That problem is NP-complete, but we're only looking for subsets of 3 elements. This can be achieved in polynomial time.

Write a function that takes as input a string, and outputs that same string, with any parentheses in it balanced. Do this using the minimum number of edits.

Write a function that takes an array of integers and returns that array rotated by N positions.

For example, if N=2, given the input array [1, 2, 3, 4, 5, 6] the function should return [5, 6, 1, 2, 3, 4]

The least common multiple of a set of integers is the smallest positive integer that is a multiple of all of the integers in the set.

Write a function that takes an array of integers and efficiently calculates and returns the LCM.

Write a function that takes as input two numbers represented as strings, and returns the product of the numbers of a string.

The numbers can be arbitrarily large.

Given a file of size 1TB, containing only 32 bit integers, describe how you would efficiently sort it. You have only 2GB of memory available.

Write a function that takes a an array of integers, and returns the contiguous subsequence of integers with the largest sum.

Write a function to return the Nth number of Fibonacci sequence.