Prolog

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Prolog (short for "Programming Logic") is a declarative and logic based programming language developed in 1972 by Alain Colmerauer and Philippe Roussel. It has many applications, most notably in Artificial Intelligence for its pattern matching abilities over natural language parse trees.

Syllabus

Hello World

Exercism's classic introductory exercise. Just say "Hello, World!".

Resistor Color

Convert a resistor band's color to its numeric representation.

Reverse String

Reverse a given string.

Wedding Woes

Infer family relations from some basic facts.

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

Determine whether a given year is a leap year.

Resistor Color Duo

Convert color codes, as used on resistors, to a numeric value.

RNA Transcription

Given a DNA strand, return its RNA complement.

Scrabble Score

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

Darts

Calculate the points scored in a single toss of a Darts game.

Grains

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

Hamming

Calculate the Hamming distance between two DNA strands.

High Scores

Manage a player's High Score list.

Pangram

Determine if a sentence is a pangram.

Space Age

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

Square Root

Given a natural radicand, return its square root.

Triangle

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

Two-Fer

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

Allergies

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

Anagram

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

Armstrong Numbers

Determine if a number is an Armstrong number.

Bank Account

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

Binary

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

Binary Search

Implement a binary search algorithm.

Collatz Conjecture

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

Custom Set

Create a custom set type.

Eliud's Eggs

Help Eliud count the number of eggs in her chicken coop by counting the number of 1 bits in a binary representation.

Change the data format for scoring a game to more easily add other languages.

Flatten Array

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

Global Positioning System

Parse GPS coordinates into their individual components

Grade School

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

Isogram

Determine if a word or phrase is an isogram.

Matrix

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

Nucleotide Count

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

Perfect Numbers

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

Proverb

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

Raindrops

Convert a number into its corresponding raindrop sounds - Pling, Plang and Plong.

Roman Numerals

Convert modern Arabic numbers into Roman numerals.

Rotational Cipher

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

Series

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

Strain

Implement the `keep` and `discard` operation on collections.

Sublist

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

Sum of Multiples

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

Acronym

Convert a long phrase to its acronym.

Binary Search Tree

Insert and search for numbers in a binary tree.

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

Bottle Song

Produce the lyrics to the popular children's repetitive song: Ten Green Bottles.

Clock

Implement a clock that handles times without dates.

Complex Numbers

Implement complex numbers.

D&D Character

Randomly generate Dungeons & Dragons characters.

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.

Kindergarten Garden

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

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.

Luhn

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

Phone Number

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

Prime Factors

Compute the prime factors of a given natural number.

Protein Translation

Translate RNA sequences into proteins.

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.

Rational Numbers

Implement rational numbers.

Robot Name

Manage robot factory settings.

Robot Simulator

Write a robot simulator.

Secret Handshake

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

Sieve

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

Simple Cipher

Implement the Vigenère cipher, a simple substitution cipher.

State of Tic-Tac-Toe

Determine the game state of a match of Tic-Tac-Toe.

Twelve Days

Output the lyrics to 'The Twelve Days of Christmas'.

Yacht

Score a single throw of dice in the game Yacht.

All Your Base

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

Atbash Cipher

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

Conway's Game of Life

Implement Conway's Game of Life.

Dominoes

Make a chain of dominoes.

Floored

Find out who lives on what floor

Food Chain

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

Killer Sudoku Helper

Write a tool that makes it easier to solve Killer Sudokus

Magic Square

Check if a square is a magic square

Matching Brackets

Make sure the brackets and braces all match.

Meetup

Calculate the date of meetups.

Nth Prime

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

OCR Numbers

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

Palindrome Products

Detect palindrome products in a given range.

Parallel Letter Frequency

Count the frequency of letters in texts using parallel computation.

Pascal's Triangle

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

Pythagorean Triplet

Given an integer N, find all Pythagorean triplets for which a + b + c = N.

Resistor Color Trio

Convert color codes, as used on resistors, to a human-readable label.

Saddle Points

Detect saddle points in a matrix.

Affine Cipher

Create an implementation of the Affine cipher, an ancient encryption algorithm from the Middle East.

Binary Puzzle

Solve a binary puzzle

Cheryl's Birthday

Figure out Cheryl's Birthday

Crypto Square

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

Diamond

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

Flower Field

Mark all the flowers in a garden.

Garden Party

Figure out who brought what dish and what beverage to a garden party

Knapsack

Given a knapsack that can only carry a certain weight, determine which items to put in the knapsack in order to maximize their combined value.

Satellite

Rebuild binary trees from pre-order and in-order traversals.

Word Count

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

Wordy

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

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.