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Exercism

Objective-C

via Exercism

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Overview

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Objective-C is a thin layer on top of C, and is a "strict superset" of C, meaning that it is possible to compile any C program with an Objective-C compiler, and to freely include C language code within an Objective-C class. Objective-C derives its object syntax from Smalltalk. All of the syntax for non-object-oriented operations (including primitive variables, pre-processing, expressions, function declarations, and function calls) is identical to that of C, while the syntax for object-oriented features is an implementation of Smalltalk-style messaging.

Syllabus

  • Hello World
    • Exercism's classic introductory exercise. Just say "Hello, World!".
  • Bob
    • Bob is a lackadaisical teenager. In conversation, his responses are very limited.
  • 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.
  • Reverse String
    • Reverse a given string.
  • Space Age
    • Given an age in seconds, calculate how old someone is in terms of a given planet's solar years.
  • Sum of Multiples
    • Given a number, find the sum of all the multiples of particular numbers up to but not including that number.
  • Two Fer
    • Create a sentence of the form "One for X, one for me.".
  • ETL
    • 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.
  • Grade School
    • Given students' names along with the grade that they are in, create a roster for the school.
  • Hamming
    • Calculate the Hamming distance between two DNA strands.
  • Isogram
    • Determine if a word or phrase is an isogram.
  • Nucleotide Count
    • Given a DNA string, compute how many times each nucleotide occurs in the string.
  • Prime Factors
    • Compute the prime factors of a given natural number.
  • Raindrops
    • Convert a number into its corresponding raindrop sounds - Pling, Plang and Plong.
  • RNA Transcription
    • Given a DNA strand, return its RNA complement.
  • Atbash Cipher
    • Create an implementation of the Atbash cipher, an ancient encryption system created in the Middle East.
  • Clock
    • Implement a clock that handles times without dates.
  • Collatz Conjecture
    • Calculate the number of steps to reach 1 using the Collatz conjecture.
  • Grains
    • Calculate the number of grains of wheat on a chessboard given that the number on each square doubles.
  • Perfect Numbers
    • Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for positive integers.
  • Phone Number
    • Clean up user-entered phone numbers so that they can be sent SMS messages.
  • Robot Name
    • Manage robot factory settings.
  • Scrabble Score
    • Given a word, compute the Scrabble score for that word.
  • Secret Handshake
    • Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.
  • Series
    • Given a string of digits, output all the contiguous substrings of length `n` in that string.
  • Sieve
    • Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.
  • Strain
    • Implement the `keep` and `discard` operation on collections.
  • Sublist
    • Write a function to determine if a list is a sublist of another list.
  • 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.
  • Anagram
    • Given a word and a list of possible anagrams, select the correct sublist.
  • Beer Song
    • Produce the lyrics to that beloved classic, that field-trip favorite: 99 Bottles of Beer on the Wall.
  • Binary Search
    • Implement a binary search algorithm.
  • Crypto Square
    • Implement the classic method for composing secret messages called a square code.
  • Largest Series Product
    • Given a string of digits, calculate the largest product for a contiguous substring of digits of length n.
  • Meetup
    • Calculate the date of meetups.
  • Nth Prime
    • Given a number n, determine what the nth prime is.
  • Pangram
    • Determine if a sentence is a pangram.
  • 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.
  • Transpose
    • Take input text and output it transposed.
  • Word Count
    • Given a phrase, count the occurrences of each word in that phrase.
  • Matching Brackets
    • Make sure the brackets and braces all match.
  • Luhn
    • Given a number determine whether or not it is valid per the Luhn formula.
  • Roman Numerals
    • Convert modern Arabic numbers into Roman numerals.
  • Run-Length Encoding
    • Implement run-length encoding and decoding.

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