Exercises on the Objective-C Track | Exercism

Hello World

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

optional values

text formatting

Two Fer

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

optional values

text formatting

Bob

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

control flow if else statements

Leap

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

Gigasecond

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

Difference Of Squares

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

Reverse String

Reverse a string

Sum Of Multiples

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

Space Age

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

discriminated unions

floating point numbers

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.

Raindrops

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

text formatting

Grade School

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

ETL

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

Isogram

Determine if a word or phrase is an isogram.

Flatten Array

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

Prime Factors

Compute the prime factors of a given natural number.

Sublist

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

Clock

Implement a clock that handles times without dates.

structural equality

Triangle

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

discriminated unions

Robot Name

Manage robot factory settings.

Scrabble Score

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

Phone Number

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

Perfect Numbers

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

discriminated unions

Secret Handshake

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

bitwise operations

Atbash Cipher

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

Sieve

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

Collatz Conjecture

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

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. 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.

Beer Song

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

Word Count

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

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

Meetup

Calculate the date of meetups.

Anagram

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

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.

Largest Series Product

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

Pangram

Determine if a sentence is a pangram.

Transpose

Take input text and output it transposed.

Binary Search

Implement a binary search algorithm.

Crypto Square

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

Pascal's Triangle

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

Say

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

text formatting

Bracket Push

Roman Numerals

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

Run Length Encoding

Implement run-length encoding and decoding.

Luhn

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

RNA Transcription

Given a DNA strand, return its RNA Complement Transcription.

Grains

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

Nth Prime

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