Skip finder corrected

gistfile1.rb

class File
  
  attr_reader :pos_start_line, :eol_length
    
  def set_eol_length
    rewind
    str = gets
    @eol_length = self.pos - str.length + 1
    rewind
  end
  
  def seek_line(pos)
    if pos < 1
      seek(0)
      @pos_start_line = 0
      return gets 
    else
      seek(pos-1)
    end
	  begin   
      if self.pos == 0
        @pos_start_line = 0
        return gets
      end
      c = getc_reverse
	  end while c != $/
    seek(2, IO::SEEK_CUR)
    @pos_start_line = self.pos
    return gets
  end
  
  def getc_reverse
    c = getbyte.chr
    if self.pos > 1
      seek(-2, IO::SEEK_CUR) 
    else
      seek(0)
    end
    return c
  end
  
end

def check_range_pos(pos_start, pos_end, f, skipped)
  s1 = f.seek_line(pos_start)
  pos1 = f.pos
  n1 = s1.to_i
  l1 = s1.length - 1
  s2 = f.seek_line(pos_end)
  pos2 = f.pos_start_line-1
  n2 = s2.to_i
  l2 = s2.length - 1
  if pos1 < pos2+1
    npos = pos_count(n1, l1, n2, l2, f.eol_length)
    if npos == pos2 - pos1 + 1 + l1 + l2 + 2*f.eol_length 
      return
    else
      pos_medial = (pos1 + pos2) / 2
      check_range_pos(pos_start, pos_medial, f, skipped)
      check_range_pos(pos_medial, pos_end, f, skipped)
    end
  elsif pos1 == pos2+1 
    (n1+1).upto(n2-1) {|i| skipped << i}
    return
  else pos1 > pos2+1
    return
  end
end

def check_range_num(pos_start, pos_end, f, skipped)
  s1 = f.seek_line(pos_start)
  pos1 = f.pos
  n1 = s1.to_i
  l1 = s1.length - 1
  s2 = f.seek_line(pos_end)
  pos2 = f.pos_start_line-1
  n2 = s2.to_i
  l2 = s2.length - 1
  if pos1 < pos2+1
    npos = pos_count(n1, l1, n2, l2, f.eol_length)
    if npos == pos2 - pos1 + 1 + l1 + l2 + 2*f.eol_length 
      return
    else
      n_medial = (n1 + n2) / 2
      mpos = pos_count(n1+1, (n1+1).to_s.length, n_medial, n_medial.to_s.length, f.eol_length)
      pos_medial = pos_start + mpos
      check_range_num(pos_start, pos_medial, f, skipped)
      check_range_num(pos_medial, pos_end, f, skipped)
    end
  elsif pos1 == pos2+1 
    (n1+1).upto(n2-1) {|i| skipped << i}
    return
  else pos1 > pos2+1
    return
  end
end

def pos_count(n1, l1, n2, l2, leol)
  if l1 == l2
    res = (n2 - n1 + 1) * (l1 + leol)
  else
    res = (10**l1 - n1) * (l1 + leol) + (n2 - 10**(l2-1) + 1) * (l2 + leol)
    (l1 + 1).upto(l2 - 1){|m| res = res + (10**m - 10**(m-1)) * (m + leol)}
  end
  return res
end

fn = 'data.txt'
f = File.open(fn)
f.set_eol_length
first_num = f.gets.to_i
a = []
1.upto(first_num-1){|i| a << i}
ts1 = Time.now.to_f
check_range_pos(0, f.size-1, f, a)
ts2 = Time.now.to_f
puts "\"5/8\" type (byte) partition: "
p a
puts (ts2 - ts1).to_s + "s"
puts "--------------"
a = []
ts3 = Time.now.to_f
check_range_num(0, f.size-1, f, a)
ts4 = Time.now.to_f
f.close
puts "\"1/2\" type (number) partition: "
p a
puts (ts4 - ts3).to_s + "s"