gistfile1.rb

class Fixnum
  def digit_count
    (self == 0) ? 1 : Math.log10(self).to_i + 1
  end
end

def make_square n
  height = Math.sqrt(n)
  throw "Input incorrect" unless height == height.to_i
  x = ((height - 1) / 2).floor
  y = ((height - 1)/2).ceil
  height = height.to_i
  direction = 0
  mat = []
  (0 .. n - 1).each do |i|
    mat[y]= [] if mat[y].nil?
    mat[y][x]= i + 1
    case direction
      when 0 then x += 1; direction = 1 if x == height - 1 || mat[y - 1].nil? || mat[y - 1][x].nil?
      when 1 then y -= 1; direction = 2 if y == 0 || mat[y].nil? || mat[y][x - 1].nil?
      when 2 then x -= 1; direction = 3 if x == 0 || mat[y + 1].nil? || mat[y + 1][x].nil?
      when 3 then y += 1; direction = 0 if y == height - 1 || mat[y].nil? || mat[y][x + 1].nil?
    end
  end
  print_square mat, n
end

def print_square mat, n
  spaces = n.digit_count + 1
  for arr in mat
    for i in arr
      print i.to_s+(" " * (spaces - i.digit_count))
    end
    print "\n"
  end
end

make_square 25