Exercises on the Elixir Track | Exercism

🎉 Exercism Research is now launched. Help Exercism, help science and have some fun at research.exercism.io 🎉

Hello World

The classical introductory exercise. Just say "Hello, World!"

RNA Transcription

Given a DNA strand, return its RNA Complement Transcription.

Word Count

Given a phrase, count the occurrences of each word in that phrase.

Roman Numerals

Write a function to convert from normal numbers to Roman Numerals.

pattern matching

Bob

Bob is a lackadaisical teenager. In conversation, his responses are very limited.

string processing

Beer Song

Produce the lyrics to that beloved classic, that field-trip favorite: 99 Bottles of Beer on the Wall.

pattern matching

Robot Simulator

Write a robot simulator.

pattern matching

List Ops

Implement basic list operations

Markdown

Refactor a Markdown parser

Bank Account

Simulate a bank account supporting opening/closing, withdraws, and deposits of money. Watch out for concurrent transactions!

Zipper

Creating a zipper for a binary tree.

Bowling

Score a bowling game

pattern matching

Forth

Implement an evaluator for a very simple subset of Forth

Nucleotide Count

Given a DNA string, compute how many times each nucleotide occurs in the string.

string processing

Secret Handshake

Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.

binary representation

Rotational Cipher

Create an implementation of the rotational cipher, also sometimes called the Caesar cipher.

string processing

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.

Protein Translation

Translate RNA sequences into proteins.

pattern matching

string processing

Pig Latin

Implement a program that translates from English to Pig Latin

pattern matching

string processing

Space Age

Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.

pattern matching

Twelve Days

Output the lyrics to 'The Twelve Days of Christmas'

string formatting

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.

Acronym

Convert a long phrase to its acronym

string processing

Series

Given a string of digits, output all the contiguous substrings of length `n` in that string.

string processing

Raindrops

Convert a number to a string, the content of which depends on the number's factors.

Run Length Encoding

Implement run-length encoding and decoding.

Sublist

Write a function to determine if a list is a sublist of another list.

Scrabble Score

Given a word, compute the Scrabble score for that word.

Sum Of Multiples

Given a number, find the sum of all the multiples of particular numbers up to but not including that number.

Pangram

Determine if a sentence is a pangram.

Simple Linked List

Write a simple linked list implementation that uses Elements and a List

Anagram

Given a word and a list of possible anagrams, select the correct sublist.

Matrix

Given a string representing a matrix of numbers, return the rows and columns of that matrix.

string processing

Matching Brackets

Make sure the brackets and braces all match.

Phone Number

Clean up user-entered phone numbers so that they can be sent SMS messages.

string processing

pattern matching

Nth Prime

Given a number n, determine what the nth prime is.

All Your Base

Convert a number, represented as a sequence of digits in one base, to any other base.

Hamming

Calculate the Hamming difference between two DNA strands.

string processing

Triangle

Determine if a triangle is equilateral, isosceles, or scalene.

Isogram

Determine if a word or phrase is an isogram.

Grade School

Given students' names along with the grade that they are in, create a roster for the school

Tournament

Tally the results of a small football competition.

string processing

Flatten Array

Take a nested list and return a single list with all values except nil/null

Leap

Given a year, report if it is a leap year.

Kindergarten Garden

Given a diagram, determine which plants each child in the kindergarten class is responsible for.

string processing

ETL

We are going to do the `Transform` step of an Extract-Transform-Load.

string processing

Meetup

Calculate the date of meetups.

pattern matching

Grains

Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.

Change

Correctly determine change to be given using the least number of coins

Parallel Letter Frequency

Count the frequency of letters in texts using parallel computation.

Binary

Convert a binary number, represented as a string (e.g. '101010'), to its decimal equivalent using first principles

binary operators

Scale Generator

Generate musical scales, given a starting note and a set of intervals.

string processing

Luhn

Given a number determine whether or not it is valid per the Luhn formula.

string processing

Gigasecond

Given a moment, determine the moment that would be after a gigasecond has passed.

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.

Pascal's Triangle

Compute Pascal's triangle up to a given number of rows.

Saddle Points

Detect saddle points in a matrix.

string processing

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).

string processing

Diamond

Given a letter, print a diamond starting with 'A' with the supplied letter at the widest point.

Binary Search

Implement a binary search algorithm.

Binary Search Tree

Insert and search for numbers in a binary tree.

Prime Factors

Compute the prime factors of a given natural number.

pattern matching

Perfect Numbers

Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for natural numbers.

pattern matching

Diffie Hellman

Diffie-Hellman key exchange.

Sieve

Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.

Wordy

Parse and evaluate simple math word problems returning the answer as an integer.

Atbash Cipher

Create an implementation of the atbash cipher, an ancient encryption system created in the Middle East.

Simple Cipher

Implement a simple shift cipher like Caesar and a more secure substitution cipher

string processing

Largest Series Product

Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.

Crypto Square

Implement the classic method for composing secret messages called a square code.

Pythagorean Triplet

There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product a * b * c.

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

Palindrome Products

Detect palindrome products in a given range.

Rail Fence Cipher

Implement encoding and decoding for the rail fence cipher.

string processing

Minesweeper

Add the numbers to a minesweeper board

Connect

Compute the result for a game of Hex / Polygon

string processing

Difference Of Squares

Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.

Poker

Pick the best hand(s) from a list of poker hands.

DOT DSL

Write a Domain Specific Language similar to the Graphviz dot language

Custom Set

Create a custom set type.

Clock

Implement a clock that handles times without dates.

Grep

Search a file for lines matching a regular expression pattern. Return the line number and contents of each matching line.

Say

Given a number from 0 to 999,999,999,999, spell out that number in English.

pattern matching

OCR Numbers

Given a 3 x 4 grid of pipes, underscores, and spaces, determine which number is represented, or whether it is garbled.

Collatz Conjecture

Calculate the number of steps to reach 1 using the Collatz conjecture

Dominoes

Make a chain of dominoes.

Transpose

Take input text and output it transposed.

ISBN Verifier

Check if a given string is a valid ISBN-10 number.

string processing

Spiral Matrix

Given the size, return a square matrix of numbers in spiral order.

Alphametics

Write a function to solve alphametics puzzles.

Two Fer

Create a sentence of the form "One for X, one for me."

Armstrong Numbers

Determine if a number is an Armstrong number

D&D Character

Randomly generate Dungeons & Dragons characters

Resistor Color

Convert a resistor band's color to its numeric representation