intervals.rb

# https://www.codewars.com/kata/52b7ed099cdc285c300001cd/train/ruby

require 'pry'

def sum_of_intervals(intervals)
  res = intervals
  del = []
  new_res = []
  stop = false

  while true do
    res.each_with_index do |root_interval, index|
      res[(index + 1)...res.size].each do |interval|
        # root поглощает проверяемый интервал
        if root_interval[0] < interval[0] && root_interval[1] > interval[1]
          new_res << root_interval if new_res.index(root_interval).nil?
          del << interval if del.index(interval).nil?
          next
        end

        # проверяемый поглощает root
        if interval[0] < root_interval[0] && interval[1] > root_interval[1]
          new_res << interval if new_res.index(interval).nil?
          del << root_interval if del.index(root_interval).nil?
          next
        end

        #обьединение
        if root_interval[1] > interval[0] && root_interval[1] <= interval[1] || (interval[1] > root_interval[0] && interval[1] <= root_interval[1])
          new_int = [[root_interval[0], interval[0]].min, [root_interval[1], interval[1]].max]
          new_res << new_int if new_res.index(new_int).nil?
          del << root_interval if del.index(root_interval).nil? && new_int != root_interval
          del << interval if del.index(interval).nil? && new_int != interval
          next
        end

        # если не одно действие не сработал, добавляем оба элемента
        new_res << root_interval if new_res.index(root_interval).nil?
        new_res << interval if new_res.index(interval).nil?
      end

      # p "res: #{res}"
      # p "new_res: #{new_res}"
      # p "del: #{del}"
      # p "~~~~~~~~~~~~"
    end
    if new_res - del == new_res && del.empty?
      stop = true
    end

    new_res = new_res - del
    del = []
    res = new_res if new_res.any?
    new_res = []

    break if stop
  end

  res.inject(0) { |sum, interval| sum += interval[1] - interval[0] }
end

i1 = [[4,10], [5,7], [5,7], [4, 15], [1, 10], [20, 25]]
i2 = [[4,10]]
i3 = [[4,10], [4,10]]
i4 = [[394, 466], [298, 396], [-228, 132], [-239, 397], [224, 397], [406, 427], [-403, 154], [8, 268], [-194, -59], [384, 423], [-68, 91]]


puts "#{sum_of_intervals(i1)} == 19"
puts "#{sum_of_intervals(i2)} == 6"
puts "#{sum_of_intervals(i3)} == 6"
puts "#{sum_of_intervals(i4)} == 869"