# Erlang

One of the easiest ways to add new exercises to the Erlang track is to translate them from other language tracks on Exercism. This page lists all of the problem specifications in the common pool of exercises which have not yet been implemented in Erlang.

The icon links to the language-independent description of the problem.

The icon links to the canonical test data.

We also link to all the implementations of each exercise in other languages, which you can use for inspiration.

Once you've picked an exercise, follow the instructions in this guide and submit your pull request to the Erlang track repository on GitHub.

### Raindrops

Convert a number to a string, the contents of which depend on the number's factors.

### Pascals Triangle

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

### Robot Name

Manage robot factory settings.

### Acronym

Convert a long phrase to its acronym

### Nth Prime

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

### Perfect Numbers

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

### Prime Factors

Compute the prime factors of a given natural number.

### Bracket Push

Make sure the brackets and braces all match.

### Crypto Square

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

### Pig Latin

Implement a program that translates from English to Pig Latin

### 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.

### Run Length Encoding

Implement run-length encoding and decoding.

### Say

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

### Minesweeper

Add the numbers to a minesweeper board

### Secret Handshake

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

### Sublist

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

### Wordy

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

### Flatten Array

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

### Binary Search Tree

Insert and search for numbers in a binary tree.

### Diamond

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

### List Ops

Implement basic list operations

### Ocr Numbers

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

### Bowling

Score a bowling game

### Change

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

### Palindrome Products

Detect palindrome products in a given range.

### Pythagorean Triplet

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

Detect saddle points in a matrix.

### Food Chain

Generate the lyrics of the song 'I Know an Old Lady Who Swallowed a Fly'

### Kindergarten Garden

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

### Matrix

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

### Protein Translation

Translate RNA sequences into proteins.

### React

Implement a basic reactive system.

### Simple Cipher

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

### Transpose

Take input text and output it transposed.

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

### Connect

Compute the result for a game of Hex / Polygon

### Forth

Implement an evaluator for a very simple subset of Forth

### House

Output the nursery rhyme 'This is the House that Jack Built'.

### Isbn Verifier

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

### Tournament

Tally the results of a small football competition.

### Twelve Days

Output the lyrics to 'The Twelve Days of Christmas'

### Alphametics

Write a function to solve alphametics puzzles.

### Dominoes

Make a chain of dominoes.

### Poker

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

### Book Store

To try and encourage more sales of different books from a popular 5 book series, a bookshop has decided to offer discounts of multiple-book purchases.

### Rail Fence Cipher

Implement encoding and decoding for the rail fence cipher.

### Diffie Hellman

Diffie-Hellman key exchange.

### Rectangles

Count the rectangles in an ASCII diagram.

### Two Bucket

Given two buckets of different size, demonstrate how to measure an exact number of liters.

### Variable Length Quantity

Implement variable length quantity encoding and decoding.

### Markdown

Refactor a Markdown parser

### Pov

Reparent a graph on a selected node

### Proverb

For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.

### Word Search

Create a program to solve a word search puzzle.

### Zebra Puzzle

Solve the zebra puzzle.

### Error Handling

Implement various kinds of error handling and resource management

### Grep

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

Reverse a string

### Scale Generator

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

### Armstrong Numbers

Determine if a number is an Armstrong number

### Dot Dsl

Write a Domain Specific Language similar to the Graphviz dot language

### Go Counting

Count the scored points on a Go board.

### Sgf Parsing

Parsing a Smart Game Format string.

### Tree Building

Refactor a tree building algorithm.

### Hangman

Implement the logic of the hangman game using functional reactive programming.

### Ledger

Refactor a ledger printer.

### Paasio

Report network IO statistics