function letterCounter(s: string): string {
  return `${s.slice(0,-2)}${parseInt(s.slice(-2,-1))+1}${s.slice(-1)}`
}

function runLengthEncoding(text: string): string {
  return text.split('').reduce((acc,cur) => {
    if(cur === acc.slice(-1)) {
      acc = letterCounter(acc)
    } else {
      acc = `${acc}1${cur}`
    }
    return acc;
  },`0${text.slice(0,1)}`)
}

// No modificar: necesario para evaluar el resultado.
export { runLengthEncoding };