counting_sort.rb

# frozen_string_literal: true

# Sort an array using the CountSort algorithm
class CountSort
  attr_reader :array_sorted

  def initialize
    @array_sorted = []
  end

  # min_max[0] = menor valor
  # min_max[1] = maior valor
  def init(array)
    min_max = array_max_min(array)
    count_sort(array, min_max[0], min_max[1])
  end

  private

  def array_max_min(array)
    array.minmax
  end

  def count_sort(array, min, max)
    return "algo deu errado pqp" if min > max

    n = max - min + 1
    size = array.length
    aux = Array.new(size)
    count = Array.new(n, 0)

    (0...size).each do |i|
      count[array[i] - min] += 1
    end
    (1...n).each do |i|
      count[i] += count[i - 1]
    end
    (0...size).each do |i|
      aux[count[array[i] - min] - 1] = array[i]
      count[array[i] - min] -= 1
    end
    (0...size).each do |i|
      array[i] = aux[i]
    end

    @array_sorted = array
  end
end

# test
c_s = CountSort.new
c_s.init([1, 4, 10, 2, 3, 32, 0])
p c_s.array_sorted