Exercises on the PHP Track | Exercism

Hello World

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

optional values

text formatting

Hamming

Calculate the Hamming difference between two DNA strands.

Gigasecond

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

Bob

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

control flow if else statements

RNA Transcription

Given a DNA strand, return its RNA Complement Transcription.

Luhn

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

Isogram

Determine if a word or phrase is an isogram.

Robot Name

Manage robot factory settings.

Difference Of Squares

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

Grade School

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

Robot Simulator

Write a robot simulator.

Run Length Encoding

Implement run-length encoding and decoding.

text formatting

Largest Series Product

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

Raindrops

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

text formatting

Pangram

Determine if a sentence is a pangram.

Roman Numerals

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

control flow loops

Sieve

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

Pig Latin

Implement a program that translates from English to Pig Latin

Leap

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

Word Count

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

Anagram

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

Trinary

Convert a trinary number, represented as a string (e.g. '102012'), to its decimal equivalent using first principles.

Bowling

Score a bowling game

control flow loops

Clock

Implement a clock that handles times without dates.

structural equality

Wordy

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

Connect

Compute the result for a game of Hex / Polygon

Minesweeper

Add the numbers to a minesweeper board

Change

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

Phone Number

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

Beer Song

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

text formatting

Atbash Cipher

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

Bracket Push

Binary

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

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.

extension methods

Variable Length Quantity

Implement variable length quantity encoding and decoding.

bitwise operations

Acronym

Convert a long phrase to its acronym

Nucleotide Count

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

Triangle

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

ETL

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

Space Age

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

floating point numbers

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

Markdown

Refactor a Markdown parser

Grains

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

floating point numbers

OCR Numbers

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

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.

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.

Scrabble Score

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

control flow loops

Perfect Numbers

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

Sum Of Multiples

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

Pascal's Triangle

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

Nth Prime

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

Binary Search

Implement a binary search algorithm.

Prime Factors

Compute the prime factors of a given natural number.

Flatten Array

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

Collatz Conjecture

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

control flow conditionals

control flow loops

Crypto Square

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

Series

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

Transpose

Take input text and output it transposed.

text formatting

Meetup

Calculate the date of meetups.

All Your Base

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

Palindrome Products

Detect palindrome products in a given range.

Rail Fence Cipher

Implement encoding and decoding for the rail fence cipher.

text formatting

Affine Cipher

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

Diamond

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

Two Fer

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