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class Polynomial | |
def initialize(values) | |
raise ArgumentError.new('Need at least 2 coefficients') unless !values.nil? && values.compact.size >= 2 | |
@terms = to_terms(values.compact) | |
end | |
def to_s | |
return "0" if all_zero | |
@terms.reject { |t| t.value == 0 }.collect { |t| t.value < 0 || t == @terms.first ? t.to_s : "+#{t.to_s}" }.to_s | |
end | |
private | |
def to_terms(values) | |
power = values.size | |
@terms = values.collect {|v| Term.new(v, power-=1)} | |
end | |
def all_zero | |
@terms.each {|t| return false if t.value != 0} | |
return true | |
end | |
end | |
class Term | |
attr_reader :value, :power | |
def initialize(value, power, isFirstTerm = false) | |
@value, @power = value, power | |
end | |
def to_s | |
"#{format_value}#{format_power}" | |
end | |
private | |
def format_value | |
return "-" if value == -1 | |
return "" if value == 1 | |
return value | |
end | |
def format_power | |
return "" if power == 0 | |
return "x" if power == 1 | |
return "x^#{power}" | |
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 | |
Test::Unit::UI::Console::TestRunner.run(Polynomial_Test) |
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