Exercises on the Elm Track | Exercism

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Hello World

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

Two Fer

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

Bob

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

text formatting

Difference Of Squares

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

Gigasecond

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

Leap

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

RNA Transcription

Given a DNA strand, return its RNA Complement Transcription.

Space Age

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

floating point numbers

Sum Of Multiples

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

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.

Collatz Conjecture

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

ETL

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

Grade School

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

Grains

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

Hamming

Calculate the Hamming difference between two DNA strands.

Nucleotide Count

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

Pangram

Determine if a sentence is a pangram.

Raindrops

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

text formatting

Armstrong Numbers

Determine if a number is an Armstrong number

Binary Search

Implement a binary search algorithm.

Isogram

Determine if a word or phrase is an isogram.

Phone Number

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

Robot Simulator

Write a robot simulator.

Scrabble Score

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

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.

Triangle

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

Acronym

Convert a long phrase to its acronym

All Your Base

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

Allergies

Given a person's allergy score, determine whether or not they're allergic to a given item, and their full list of allergies.

bitwise operations

Anagram

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

Largest Series Product

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

List Ops

Implement basic list operations

Pascal's Triangle

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

Series

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

Twelve Days

Output the lyrics to 'The Twelve Days of Christmas'

text formatting

Word Count

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

Atbash Cipher

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

Luhn

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

Pythagorean Triplet

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

Roman Numerals

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

Run Length Encoding

Implement run-length encoding and decoding.

Transpose

Take input text and output it transposed.

Matching Brackets

Make sure the brackets and braces all match.

Sublist

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

Say

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

text formatting

Wordy

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