the-deaf-rats-of-hamelin.md

The Deaf Rats of Hamelin ^{6 Kyu}

^{LINK TO THE KATA - FUNDAMENTALS STRINGS ALGORITHMS QUEUES DATA STRUCTURES}

Description

Story

The Pied Piper has been enlisted to play his magical tune and coax all the rats out of town.

But some of the rats are deaf and are going the wrong way!

Kata Task

How many deaf rats are there?

Legend

P = The Pied Piper O~ = Rat going left ~O = Rat going right

Example

ex1 ~O~O~O~O P has 0 deaf rats

ex2 P O~ O~ ~O O~ has 1 deaf rat

ex3 ~O~O~O~OP~O~OO~ has 2 deaf rats

Solution

const piedPiper = 'P'
const ratGoingLeft = 'O~'
const ratGoingRight = '~O'

const removeBlankSpaces = string => string.replace(/\s/g, '')

const addASpaceEveryTwoCharacters = string => {
  if (string === '') return ''
  return string.match(/.{1,2}/g).join(' ')
}

const getDeafRats = (rats, rat) => {
  const regularExpresion = new RegExp(rat, 'g')
  return (rats.match(regularExpresion) || []).length
}

const countDeafRats = town => {
  const rats = removeBlankSpaces(town).split(piedPiper)

  const ratsLeft = addASpaceEveryTwoCharacters(rats[0])
  const ratsRight = addASpaceEveryTwoCharacters(rats[1])

  const deafRatsLeft = getDeafRats(ratsLeft, ratGoingLeft)
  const deafRatsRight = getDeafRats(ratsRight, ratGoingRight)

  return deafRatsLeft + deafRatsRight
}