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class Polynomial | |
def initialize(polynomial) | |
if polynomial.length < 2 | |
raise ArgumentError.new("Need at least 2 coefficients") | |
else | |
@polynomial = [] | |
polynomial.reverse.each_with_index do |x, i| | |
@polynomial << Term.new(x, i, (i == (polynomial.size - 1))) | |
end | |
end | |
end | |
def to_s | |
res = @polynomial.reverse.map(&:to_s).join("") | |
end | |
class Term | |
def initialize(coefficient, degree, first_term = false) | |
@coefficient = coefficient | |
@degree = Degree.new(degree) | |
@first_term = first_term | |
end | |
def to_s | |
case @coefficient.abs | |
when 0 | |
@first_term ? "0" : "" | |
when 1 | |
if @degree.value == 0 | |
"#{@coefficient}" | |
else | |
"#{sign}#{@degree.to_s}" | |
end | |
else | |
"#{sign}#{@coefficient.abs}#{@degree.to_s}" | |
end | |
end | |
def sign | |
if @coefficient < 0 | |
"-" | |
elsif @coefficient >= 0 && @first_term | |
"" | |
else | |
"+" | |
end | |
end | |
class Degree | |
def initialize(degree) | |
@degree = degree | |
end | |
def value | |
@degree | |
end | |
def to_s | |
case @degree | |
when 0 | |
"" | |
when 1 | |
"x" | |
else | |
"x^#{@degree}" | |
end | |
end | |
end | |
end | |
end |
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# assuming that your solution is polynomial.rb | |
require 'test/unit' | |
require 'test/unit/ui/console/testrunner' | |
require 'polynomial' | |
class Polynomial_Test < Test::Unit::TestCase | |
def setup | |
@p1 = Polynomial.new([-3,-4,1,0,6]) | |
@p2 = Polynomial.new([1,0,2]) | |
@p3 = Polynomial.new([-1,-2,3,0]) | |
@p4 = Polynomial.new([0,0,0]) | |
end | |
def test_first_negative | |
assert_equal("-3x^4-4x^3+x^2+6", @p1.to_s) | |
end | |
def test_simple | |
assert_equal("x^2+2", @p2.to_s) | |
end | |
def test_first_minus_one | |
assert_equal("-x^3-2x^2+3x", @p3.to_s) | |
end | |
def test_all_zero | |
assert_equal("0", @p4.to_s) | |
end | |
def test_error | |
e = assert_raise(ArgumentError) { Polynomial.new([1]) } | |
assert_match(/Need at least 2 coefficients/, e.message) | |
end | |
end | |
class Term_Test < Test::Unit::TestCase | |
def test_zero_first_term | |
term = Polynomial::Term.new(0, 0, true) | |
assert_equal("0", term.to_s) | |
end | |
def test_zero_term | |
term = Polynomial::Term.new(0, 0) | |
assert_equal("", term.to_s) | |
end | |
def test_one_coefficient_zero_degree | |
term = Polynomial::Term.new(1, 0) | |
assert_equal("1", term.to_s) | |
end | |
def test_one_coefficient | |
term = Polynomial::Term.new(1, 1, true) | |
assert_equal("x", term.to_s) | |
end | |
def test_negative | |
term = Polynomial::Term.new(-1, 1) | |
assert_equal("-x", term.to_s) | |
end | |
def test_positive_first | |
term = Polynomial::Term.new(1, 1, true) | |
assert_equal("x", term.to_s) | |
end | |
end | |
class Degree_Test < Test::Unit::TestCase | |
def test_zero | |
degree = Polynomial::Term::Degree.new(0) | |
assert_equal("", degree.to_s) | |
end | |
def test_one | |
degree = Polynomial::Term::Degree.new(1) | |
assert_equal("x", degree.to_s) | |
end | |
def test_mode | |
degree = Polynomial::Term::Degree.new(2) | |
assert_equal("x^2", degree.to_s) | |
end | |
end | |
Test::Unit::UI::Console::TestRunner.run(Polynomial_Test) | |
Test::Unit::UI::Console::TestRunner.run(Term_Test) | |
Test::Unit::UI::Console::TestRunner.run(Degree_Test) |
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