Scala solutions for the Coding Kata programming exercises

backwards-talk-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  /**
   * Revert a word in 'backward talk' to understand it
   *
   * @param word  the backwards word
   * @return      the regular word
   */
  def revert(word: String) = word reverse

}

cough-syrup-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  def gcd(dividend: Int, divisor: Int): Int = (dividend % divisor) match {
    case 0 => divisor
    case x => gcd(divisor, x)
  }

  /**
   * Calculate the 'greatest common divisor'.
   *
   * @param number1 the first number ('numerator')
   * @param number2 the second number ('denominator')
   *
   * @return GCD of number1 and number2
   */
  def calcGCD(n1: Int, n2: Int) = if (n1 == 0) n2 else gcd(n2, n1)

}

fibonacci-killer-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  /**
   * Calculate an element of the Fibonacci sequence
   *
   * @param n     element number
   * @return      n-th element of the Fibonacci sequence
   */
  def fibonacci(n: Int): Int = n match {
    case x if x <= 1 => x
    case x => fibonacci(n-1) + fibonacci(n-2)
  }

}

fizz-buzz-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  /**
   * Give an answer to the current game
   *
   * @param number    current number in the game sequence
   * @return          appropriate answer to the current number
   */
  def answer(number: Int) = {
    var answer = ""
    if (number % 3 == 0) answer += "fizz"
    if (number % 5 == 0) answer += "buzz"
    if (answer == "") number.toString else answer
  }

}

nasa-countdown-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  /**
   * Issue the NASA countdown
   *
   * @param start    number to start with
   * @return         array with numbers from 'start' to 0
   */
  def countdown(start: Int) = (for (i <- (start to 0 by -1)) yield new Integer(i)).toArray

}

tea-party-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  /**
   * Welcome a guest
   *
   * @param lastName   the last name of the guest
   * @param isWoman    true if the guest is female
   * @param isSir      true if the guest was knighted by the queen
   *
   * @return          issues welcome text to the guest
   */
  def welcome(lastName: String, isWoman: Boolean, isSir: Boolean) =
      "Hello %s %s".format(if (isWoman) if (isSir) "Dame" else "Ms." else if (isSir) "Sir" else "Mr.", lastName)

}

teleprompter-1.scala

package org.codingkata.unit;

import _root_.org.codingkata.unit.api.BaseKataSolution;

class MyKata extends BaseKataSolution {

  lazy val Slang = """\$([\w ]*)\$""".r

  /**
   * Translate a slang text to a TV news-compatible text
   *
   * @param text string full of slang (e.g. 'I am $kewl$.')
   * @param dictionary slang dictionary - in pairs, like {{slang, non-slang}, ...}
   *
   * @return the 'cleaned' text
   */
  def translate(text: String, slang: Array[Array[String]]) = {
    lazy val dict = List.fromArray(slang).foldLeft(Map.empty[String, String])((d, s) => d + (s(0) -> s(1)))
    Slang.replaceAllIn(text, m => dict(m.group(1)))
  }

}