2016-10-15 21:27:06 homework submit

ruby_intro.rb

@@ -0,0 +1,54 @@
+# homework done by alansnape on Oct. 12th
+# Ojyoosama kyoo mo miyabiyaka desu.
+
+# Part 1
+
+def sum arr
+	return arr.inject(0, :+)
+end
+
+def max_2_sum arr
+	return sum(arr.sort.reverse[0..1])
+end
+
+def sum_to_n? arr, n
+	ret = false
+	arr.each_with_index do |oi, i|
+		arr.each_with_index do |oj, j|
+			ret ||= (i != j && oi + oj == n)
+		end
+	end
+	return ret
+end
+
+# Part 2
+
+def hello(name)
+	return 'Hello, ' + name
+end
+
+def starts_with_consonant? s
+	return (s[0] =~ /[[:alpha:]]/) && ! (s[0] =~ /[aeiouAEIOU]/)
+end
+
+def binary_multiple_of_4? s
+	return (s =~ /^[01]+$/) && (s =~ /100$/ || s == '0')
+end
+
+# Part 3
+
+class BookInStock
+	attr_accessor :isbn, :price
+
+	def initialize _isbn, _p
+		if _isbn.empty? || _p <= 0 then
+			raise ArgumentError
+		end
+		self.isbn = _isbn
+		self.price = _p
+	end
+
+	def price_as_string
+		return format("$%.2f", self.price)
+	end
+end