triangle.rb

# Triangle Project Code.

# Triangle analyzes the lengths of the sides of a triangle
# (represented by a, b and c) and returns the type of triangle.
#
# It returns:
#   :equilateral  if all sides are equal
#   :isosceles    if exactly 2 sides are equal
#   :scalene      if no sides are equal
#
# The tests for this method can be found in
#   about_triangle_project.rb
# and
#   about_triangle_project_2.rb
#
def triangle(a, b, c)
  x,y,z = [a,b,c].sort
  raise TriangleError, "negative sides" if [x,y,z].min <= 0
  raise TriangleError, "hypotenuse cannot be greater than sum of legs" if x+y<=z

  equal_sides = [ (x==y), (y==z), (z==x) ].select { |side| side}

  case equal_sides.size
  when 0 then :scalene
  when 1 then :isosceles
  when 3 then :equilateral
  else raise TriangleError, "general triangle error"
  end
end

# Error class used in part 2.  No need to change this code.
class TriangleError < StandardError
end