optimization_task.rb

  def solution(array)
    max_distance = 0
    indexes = {}

    array.each_with_index do |item, index|
      if indexes.keys.include?(array[index])
        max_distance = [max_distance, index - indexes[array[index]]].max
      else
        indexes[array[index]] = index
      end
    end

    max_distance
  end

optimization_task_2.rb

class Task
  def solution array
    sum = array.inject(:+)
    n = array.count
    left_sum = 0

    array.each_with_index do |el, i|
      sum -= array[i]

      return i if left_sum == sum

      left_sum += array[i]
    end

    return -1
  end

  def solution2(a)
    n = a.length
    result = 0

    for i in 0 .. (n - 1)
      for j in 0 .. (n - 1)
        if (a[i] == a[j]) then
          if (i - j).abs > result then
            result = (i - j).abs
          end
        end
      end
    end
    return result
  end

  def solution3(array)
    max_distance = 0

    indexes = {}

    array.each_with_index do |item, index|
      if indexes.keys.include?(array[index])
        max_distance = [max_distance, index - indexes[array[index]]].max
      else
        indexes[array[index]] = index
      end
    end

    max_distance
  end
end

optimization_task_2_spec.rb

describe Task do
  describe 'solution' do
    subject { Task.new.solution a }

    context '1' do
      let(:a) { [-1, 3, -4, 5, 1, -6, 2, 1] }

      it { is_expected.to eq 1 }
    end

    context '2' do
      let(:a) { [1,2,3,4] }

      it { is_expected.to eq -1 }
    end
  end

  describe 'solution2' do
    subject { Task.new.solution2 a }

    context '1' do
      let(:a) { [4,6,2,2,6,6,1] }

      it { is_expected.to eq 4 }
    end
  end

  describe 'solution3' do
    subject { Task.new.solution3 a }

    context '1' do
      let(:a) { [4,6,2,2,6,6,1] }

      it { is_expected.to eq 4 }
    end
  end
end