Saddle Points

saddle_points.rb

class Matrix
  def initialize(raw_data_string)
    @data = raw_data_string
  end

  def rows
    format @data
  end

  def columns
    rows.transpose
  end

  def saddle_points
    marked_rows = mark_potential_row_saddle_points rows
    organized_rows = organize_rows_for_column_matching(marked_rows).flatten
    marked_columns = mark_potential_column_saddle_points(columns).flatten
    potential_saddle_points = marked_columns.zip(organized_rows)

    potential_saddle_points.reject { |coordinate| coordinate.include? nil }
  end

  private

  def mark_potential_row_saddle_points(rows)
    rows.map do |row|
      highest_number = row.sort.last
      row.each_index.map do |index|
        index if row[index] >= highest_number
      end
    end
  end

  def mark_potential_column_saddle_points(columns)
    columns.map do |column|
      lowest_number = column.sort.first
      column.each_index.map do |index|
        index if column[index] <= lowest_number
      end
    end
  end

  def organize_rows_for_column_matching(marked_rows)
    marked_rows.transpose
  end

  def format(raw_data_string)
    raw_data_array = raw_data_string.split("\n")

    raw_data_array.map { |number_string| number_string.split(" ").map(&:to_i) }
  end
end