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Elixir track
Exercises
Exercises on the Elixir track
Join the Elixir Track
92 exercises to help you master Elixir
easy
Hello World
The classical introductory exercise. Just say "Hello, World!"
strings
easy
Nucleotide Count
Given a DNA string, compute how many times each nucleotide occurs in the string.
enumerables
maps
string processing
easy
Secret Handshake
Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.
binary representation
easy
Rotational Cipher
Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.
string processing
easy
Strain
Implement the `keep` and `discard` operation on collections. Given a collection and a predicate on the collection's elements, `keep` returns a new collection containing those elements where the predicate is true, while `discard` returns a new collection containing those elements where the predicate is false.
collections
easy
Protein Translation
Translate RNA sequences into proteins.
pattern matching
string processing
easy
Pig Latin
Implement a program that translates from English to Pig Latin
pattern matching
string processing
easy
Space Age
Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.
pattern matching
easy
Bob
Bob is a lackadaisical teenager. In conversation, his responses are very limited.
control flow
string processing
easy
Twelve Days
Output the lyrics to 'The Twelve Days of Christmas'
enumerations
reduce
string formatting
easy
Word Count
Given a phrase, count the occurrences of each word in that phrase.
lists
maps
reduce
easy
Accumulate
Implement the `accumulate` operation, which, given a collection and an operation to perform on each element of the collection, returns a new collection containing the result of applying that operation to each element of the input collection.
recursion
reduce
easy
Acronym
Convert a long phrase to its acronym
string processing
easy
Series
Given a string of digits, output all the contiguous substrings of length `n` in that string.
string processing
easy
Raindrops
Convert a number to a string, the contents of which depend on the number's factors.
conditionals
easy
Run Length Encoding
Implement run-length encoding and decoding.
algorithms
strings
easy
Sublist
Write a function to determine if a list is a sublist of another list.
lists
enumeration
easy
Scrabble Score
Given a word, compute the scrabble score for that word.
reduce
easy
Sum Of Multiples
Given a number, find the sum of all the multiples of particular numbers up to but not including that number.
algorithms
reduce
math
easy
Pangram
Determine if a sentence is a pangram.
enumerations
strings
easy
Simple Linked List
Write a simple linked list implementation that uses Elements and a List
recursion
easy
Anagram
Given a word and a list of possible anagrams, select the correct sublist.
filter
enumeration
easy
Matrix
Given a string representing a matrix of numbers, return the rows and columns of that matrix.
string processing
structs
easy
Bracket Push
Make sure the brackets and braces all match.
algorithms
reduce
enumeration
easy
RNA Transcription
Given a DNA strand, return its RNA Complement Transcription.
strings
easy
Phone Number
Clean up user-entered phone numbers so that they can be sent SMS messages.
string processing
pattern matching
easy
Nth Prime
Given a number n, determine what the nth prime is.
algorithms
recursion
math
easy
Roman Numerals
Write a function to convert from normal numbers to Roman Numerals.
algorithms
pattern matching
easy
All Your Base
Convert a number, represented as a sequence of digits in one base, to any other base.
translation
numbers
math
easy
Hamming
Calculate the Hamming difference between two DNA strands.
string processing
easy
Triangle
Determine if a triangle is equilateral, isosceles, or scalene.
algorithms
easy
Beer Song
Produce the lyrics to that beloved classic, that field-trip favorite: 99 Bottles of Beer on the Wall.
recursion
pattern matching
easy
Isogram
Determine if a word or phrase is an isogram.
reduce
algorithms
easy
Grade School
Given students' names along with the grade that they are in, create a roster for the school
maps
medium
Tournament
Tally the results of a small football competition.
formatting
sorting
string processing
medium
List Ops
Implement basic list operations
lists
enumeration
recursion
easy
Flatten Array
Take a nested list and return a single list with all values except nil/null
lists
recursion
easy
Leap
Given a year, report if it is a leap year.
algorithms
easy
Kindergarten Garden
Given a diagram, determine which plants each child in the kindergarten class is responsible for.
string processing
easy
ETL
We are going to do the `Transform` step of an Extract-Transform-Load.
enumeration
string processing
medium
Meetup
Calculate the date of meetups.
time
calendar
pattern matching
easy
Grains
Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
recursion
reduce
easy
Change
Correctly determine change to be given using the least number of coins
enumeration
reduce
medium
Parallel Letter Frequency
Count the frequency of letters in texts using parallel computation.
concurrency
otp
easy
Binary
Convert a binary number, represented as a string (e.g. '101010'), to its decimal equivalent using first principles
binary operators
math
medium
Scale Generator
Generate musical scales, given a starting note and a set of intervals.
enumerations
string processing
medium
Luhn
Given a number determine whether or not it is valid per the Luhn formula.
string processing
enumeration
medium
Markdown
Refactor a Markdown parser
refactoring
easy
Gigasecond
Calculate the moment when someone has lived for 10^9 seconds.
calendar
time
medium
Queen Attack
Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.
algorithms
structs
easy
Pascal's Triangle
Compute Pascal's triangle up to a given number of rows.
enumeration
algorithms
math
medium
Saddle Points
Detect saddle points in a matrix.
matricies
string processing
enumeration
easy
Hexadecimal
Convert a hexadecimal number, represented as a string (e.g. "10af8c"), to its decimal equivalent using first principles (i.e. no, you may not use built-in or external libraries to accomplish the conversion).
numbers
string processing
math
medium
Diamond
Given a letter, print a diamond starting with 'A' with the supplied letter at the widest point.
algorithms
enumeration
easy
Binary Search
Implement a binary search algorithm.
algorithms
recursion
easy
Binary Search Tree
Insert and search for numbers in a binary tree.
algorithms
trees
easy
Prime Factors
Compute the prime factors of a given natural number.
recursion
pattern matching
math
easy
Perfect Numbers
Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for natural numbers.
pattern matching
enumeration
math
medium
Diffie Hellman
Diffie-Hellman key exchange.
math
medium
Sieve
Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.
enumeration
math
medium
Wordy
Parse and evaluate simple math word problems returning the answer as an integer.
parsers
medium
Robot Simulator
Write a robot simulator.
structs
pattern matching
otp
easy
Atbash Cipher
Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.
encryption
easy
Simple Cipher
Implement a simple shift cipher like Caesar and a more secure substitution cipher
encryption
string processing
medium
Bank Account
Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!
otp
medium
Largest Series Product
Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.
enumeration
recursion
math
medium
Crypto Square
Implement the classic method for composing secret messages called a square code.
encryption
algorithms
medium
Pythagorean Triplet
There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product a * b * c.
reduce
algorithms
math
medium
Allergies
Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.
binary operators
enumeration
medium
Palindrome Products
Detect palindrome products in a given range.
reduce
math
medium
Rail Fence Cipher
Implement encoding and decoding for the rail fence cipher.
encryption
string processing
hard
Zipper
Creating a zipper for a binary tree.
structs
recursion
trees
algorithms
medium
Minesweeper
Add the numbers to a minesweeper board
enumeration
reduce
algorithms
medium
Connect
Compute the result for a game of Hex / Polygon
string processing
reduce
medium
Difference Of Squares
Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.
reduce
math
medium
Poker
Pick the best hand(s) from a list of poker hands.
sorting
hard
Bowling
Score a bowling game
structs
algorithms
pattern matching
hard
DOT DSL
Write a Domain Specific Language similar to the Graphviz dot language
structs
graphs
medium
Custom Set
Create a custom set type.
collections
enumeration
hard
Forth
Implement an evaluator for a very simple subset of Forth
parsers
medium
Clock
Implement a clock that handles times without dates.
integers
logic
protocols
structs
transforming
easy
Grep
Search a file for lines matching a regular expression pattern. Return the line number and contents of each matching line.
enumerations
strings
easy
Say
Given a number from 0 to 999,999,999,999, spell out that number in English.
pattern matching
medium
OCR Numbers
Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.
enumerations
strings
easy
Collatz Conjecture
Calculate the number of steps to reach 1 using the Collatz conjecture
recursion
math
medium
Dominoes
Make a chain of dominoes.
algorithms
enumerations
recursion
sorting
trees
medium
Transpose
Take input text and output it transposed.
strings
transforming
easy
ISBN Verifier
Check if a given string is a valid ISBN-10 number.
string processing
medium
Spiral Matrix
Given the size, return a square matrix of numbers in spiral order.
lists
transforming
medium
Alphametics
Write a function to solve alphametics puzzles.
algorithms
backtracking
strings
easy
Two Fer
Create a sentence of the form "One for X, one for me."
strings
easy
Armstrong Numbers
Determine if a number is an Armstrong number
algorithms
math