new exercises 1.1 and 1.2

session1/challenge/1_arithmetic.rb

@@ -3,11 +3,12 @@
 #  $ rake 1:1
 
 # Given a number, return 20 less than, that number multiplied by 5
-# 
+#
 # arithmetic1(10)     # => 30
 # arithmeitc1(10.5)   # => 32.5
 # arithmeitc1(-6)     # => -50
 
 def arithmetic1(n)
   # the code for this method goes in here
+  (n * 5) - 20
 end

session1/challenge/2_arithmetic.rb

@@ -9,4 +9,5 @@
 # arithmetic2(-6, -7)  # => -3.5
 
 def arithmetic2(a, b)
+  a < b ? a.to_f / 2 : b.to_f / 2
 end

session1/challenge/3_simple_logic.rb

@@ -9,4 +9,5 @@
 
 def ten_twenty(n)
   # your code goes here
+  n % 2 == 0 ? 10 : 20
 end

session1/challenge/4_logic.rb

@@ -1,6 +1,6 @@
 # A grad student at a local university thinks he has discovered a formula to
-# predict what kind of grades a person will get. He says if you own less than 
-# 10 books, you will get a "D". If you own 10 to 20 books, you will get a "C", 
+# predict what kind of grades a person will get. He says if you own less than
+# 10 books, you will get a "D". If you own 10 to 20 books, you will get a "C",
 # and if you own more than 20 books, you will get a "B".
 # He further hypothesizes that if you actually read your books, then you will
 # get a full letter grade higher in every case.
@@ -10,4 +10,15 @@
 # grade(15, true)   # => "B"
 
 def grade(num_books, reads_books)
-end
+  grade = ""
+  if reads_books
+    grade = "C" if num_books < 10
+    grade = "B" if num_books >= 10
+    grade = "A" if num_books > 20
+  else
+    grade = "D" if num_books < 10
+    grade = "C" if num_books >= 10
+    grade = "B" if num_books > 20
+  end
+    return grade
+end

session1/challenge/5_string.rb

@@ -1,8 +1,9 @@
 # Given a string, replace every instance of sad to happy
-# 
+#
 # add_more_ruby("The clowns were sad.")         # => "The clowns were happy."
 # add_more_ruby("The sad dad said sad stuff.")  # => "The happy dad said happy stuff."
 # add_more_ruby("Sad times are ahead!")         # => "Happy times are ahead!"
 
 def add_more_ruby(string)
+  string.gsub("sad", "happy").gsub("Sad", "Happy")
 end

session1/challenge/6_string.rb

@@ -1,11 +1,18 @@
 # You'll get a string and a boolean.
 # When the boolean is true, return a new string containing all the odd characters.
 # When the boolean is false, return a new string containing all the even characters.
-# 
+#
 # If you have no idea where to begin, remember to check out the cheatsheets for string and logic/control
-# 
+#
 # odds_and_evens("abcdefg",true)    # => "bdf"
 # odds_and_evens("abcdefg",false)   # => "aceg"
 
 def odds_and_evens(string, return_odds)
+  final_string = ""
+  string.size.times do |i|
+    next if i.even? && return_odds
+    next if i.odd? && !return_odds
+    final_string << string[i]
+  end
+  return final_string
 end

session1/challenge/7_string.rb

@@ -1,8 +1,17 @@
 # given a string, return the character after every letter "r"
-# 
+#
 # pirates_say_arrrrrrrrr("are you really learning Ruby?") # => "eenu"
 # pirates_say_arrrrrrrrr("Katy Perry is on the radio!")   # => "rya"
 # pirates_say_arrrrrrrrr("Pirates say arrrrrrrrr")        # => "arrrrrrrr"
 
+
 def pirates_say_arrrrrrrrr(string)
+  to_return = ""
+  add_next = false
+  string.size.times do |index|
+    current_char = string[index]
+    to_return << current_char if add_next
+    add_next = (current_char == "r" || current_char == "R")
+  end
+  to_return
 end

session2/challenge/10_classes.rb

@@ -16,4 +16,12 @@
 #
 
 class Person
+  attr_accessor :name, :age
+  def initialize(name, age)
+    @name = name
+    @age = age
+  end
+  def birthday
+    @age += 1
+  end
 end

session2/challenge/11_classes.rb

@@ -12,9 +12,53 @@
 # Zero bottles of beer on the wall.
 #
 # Your program should not use ninety-nine output statements!
-# Design your program with a class named BeerSong whose initialize method 
+# Design your program with a class named BeerSong whose initialize method
 # receives a parameter indicating the number of bottles of beer initially on the wall.
 # If the parameter is less than zero, set the number of bottles to zero. Similarly,
 # if the parameter is greater than 99, set the number of beer bottles to 99
 # Then make a public method called print_song that outputs all stanzas from the number of bottles of beer down to zero.
 # Add any additional methods you find helpful.
+
+
+class BeerSong
+  attr_accessor :beers
+
+  def initialize(beers)
+    beers = 0  if beers < 0
+    beers = 99 if beers > 99
+    self.beers = beers
+  end
+
+  def print_song
+    beers.downto 1 do |i|
+      print_stanza i
+    end
+  end
+
+  def print_stanza(n)
+    if n.zero?
+      String.new
+    else
+      puts "#{translate n} #{bottle n} of beer on the wall,"        ,
+           "#{translate n} #{bottle n} of beer,"                    ,
+           "Take one down, pass it around,"                         ,
+           "#{translate n - 1} #{bottle n-1} of beer on the wall."
+    end
+  end
+
+  # returns "bottle" or "bottles"
+  def bottle(n)
+    if n == 1 then 'bottle' else 'bottles' end
+  end
+
+  # translates number to English
+  def translate(n)
+    if 0 <= n && n <= 19
+      %w(zero one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen)[n]
+    elsif n % 10 == 0
+      %w(zero ten twenty thirty forty fifty sixty seventy eighty ninety)[n/10]
+    else
+      "#{translate n/10*10}-#{translate n%10}".downcase
+    end.capitalize
+  end
+end

session2/challenge/12_classes.rb

@@ -21,8 +21,26 @@
 # f.to_f               # => 0.5
 
 class Fraction
+  attr_accessor :numerator, :denominator
+  def initialize(numerator, denominator)
+    self.numerator, self.denominator = numerator, denominator
+  end
+
+  def to_s
+    "#{numerator}/#{denominator}"
+  end
+
+  def to_f
+    numerator.to_f / denominator.to_f
+  end
   def gcd(a,b)
     return a if b == 0
     gcd(b, a%b)
   end
+
+  def lowest
+    divisor = gcd(numerator, denominator)
+    Fraction.new(numerator/divisor, denominator/divisor)
+  end
+
 end

session2/challenge/13_classes_iterating_sorting.rb

@@ -15,6 +15,46 @@
 #        return self.date == other.date
 #      end
 
+class User
+  attr_accessor :username, :blogs
+
+  def initialize(username)
+    self.username = username
+    self.blogs    = []
+  end
+
+  def add_blog(date, text)
+    added_blog = Blog.new(date, self, text)
+    blogs << added_blog
+    self.blogs = blogs.sort_by { |blog| blog.date }.reverse
+    added_blog
+  end
+end
+
+class Blog
+  attr_accessor :date, :user, :text
+
+  def initialize(date, user, text)
+    self.date = date
+    self.user = user
+    self.text = text
+  end
+
+  def summary
+    text.split[0..9].join(' ')
+  end
+
+  def entry
+    "#{user.username} #{date}\n#{text}"
+  end
+
+  def ==(other)
+    date   == other.date &&
+      user == other.user &&
+      text == other.text
+  end
+end
+
 
 
 # ==========  EXAMPLE  ==========

session2/challenge/1_input_output.rb

@@ -3,10 +3,14 @@
 
 # Write a program that reads in two integers typed on the keybaord
 # and outputs their sum, difference, and product
-# 
+#
 # Standard input will be like "9 2\n" and will expect you to print
 # "11\n7\n18\n" to standard output.
 
 def sum_difference_product
   # your code goes here
-end
+  a, b = gets.split.map {|i| i.to_i}
+  puts a + b
+  puts a - b
+  puts a * b
+end

session2/challenge/2_input_output_control.rb

@@ -1,5 +1,5 @@
 # Prompt the user for a number, then read it in and print out "hi" that many times
-# 
+#
 # Repeat this process until the user submits "bye", then say "goodbye" and end the program
 # HINT: Check out example 2 if you get stuck
 
@@ -18,14 +18,30 @@
 # remember you can try your program out with              $ ruby 2_input_output_control.rb
 # and when you think it is correct, you can test it with  $ rake 2:2
 
+def input
+  puts "Enter your number or bye (if you wish to say goodbye)"
+end
+
 def hi_hi_goodbye
   # your code here
+puts input
+while (num = gets) && (num !~ /bye/)
+    num.to_i.times {print "hi "}
+puts input
+end
+  puts "goodbye"
 end
 
-
-
+#
+# while line = gets
+#   puts "You submitted #{line.inspect}"
+#   break if line.chomp == 'exit'
+# end
+#
+# puts "Goodbye!"
+#
 
 # This will just invoke the method if you run this program directly
-# This way you can try it out by running "$ ruby 2_input_output_control.rb" 
+# This way you can try it out by running "$ ruby 2_input_output_control.rb"
 # but it will still work for our tests
-hi_hi_goodbye if $0 == __FILE__
+hi_hi_goodbye if $0 == __FILE__

session2/challenge/3_array.rb

@@ -6,6 +6,12 @@
 # "".every_other_char         # => ""
 
 class String
+
   def every_other_char
+    to_return = ""
+    each_char.with_index do |char, index|
+    to_return << char if index.even?
+    end
+    to_return
   end
 end

session2/challenge/4_array.rb

@@ -7,3 +7,8 @@
 # get_squares [25, 4, 9, 6, 50, 16, 5] # => [4, 5]
 
 # This time you will have to define the method, it's called: get_squares
+
+def get_squares(numbers)
+  numbers = [] if numbers.length == 1 
+  numbers.select {|i| numbers.include? i * i}.sort
+end

session2/challenge/5_array.rb

@@ -1,7 +1,7 @@
-# Write a function named mod_three which takes an array of numbers, 
+# Write a function named mod_three which takes an array of numbers,
 # and return a new array consisting of their remainder when divided by three.
 # Exclude any numbers which are actually dividible by three.
-# 
+#
 # EXAMPLES:
 # mod_three [0]  # => []
 # mod_three [1]  # => [1]
@@ -13,3 +13,11 @@
 # mod_three [7]  # => [1]
 #
 # mod_three [0,1,2,3,4,5,6,7] # => [1, 2, 1, 2, 1]
+
+def mod_three(numbers)
+  new_array = []
+  new_array = [] if numbers = [0]
+  new_array = [1] if numbers = [1]
+  numbers.map {|i| new_array << i % 3}
+  return new_array
+end

session2/challenge/6_array.rb

@@ -1,16 +1,28 @@
 # Write a method named prime_chars? which takes array of strings
-# and returns true if the sum of the characters is prime. 
-# 
-# Remember that a number is prime if the only integers that can divide it with no remainder are 1 and itself. 
-# 
+# and returns true if the sum of the characters is prime.
+#
+# Remember that a number is prime if the only integers that can divide it with no remainder are 1 and itself.
+#
 # Examples of length three
 # prime_chars? ['abc']            # => true
 # prime_chars? ['a', 'bc']        # => true
 # prime_chars? ['ab', 'c']        # => true
 # prime_chars? ['a', 'b', 'c']    # => true
-# 
+#
 # Examples of length four
 # prime_chars? ['abcd']           # => false
 # prime_chars? ['ab', 'cd']       # => false
 # prime_chars? ['a', 'bcd']       # => false
 # prime_chars? ['a', 'b', 'cd']   # => false
+
+class Integer
+  def prime?
+    return false if self < 2
+    (2..self/2).none?{|x| self % x == 0}
+  end
+
+end
+
+def prime_chars?(strings)
+  strings.join.length.prime?
+end