chore: commit previous exercises

.rubocop.yml

@@ -0,0 +1,10 @@
+require:
+  - standard
+  - standard-custom
+  - standard-performance
+  - rubocop-performance
+
+inherit_gem:
+  standard: config/base.yml
+  standard-custom: config/base.yml
+  standard-performance: config/base.yml

.solargraph.yml

@@ -0,0 +1,17 @@
+---
+include:
+- "**/*.rb"
+exclude:
+- spec/**/*
+- test/**/*
+- vendor/**/*
+- ".bundle/**/*"
+require: []
+domains: []
+reporters:
+- rubocop
+- require_not_found
+- typecheck
+require_paths: []
+plugins: []
+max_files: 5000

Gemfile

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+source "https://rubygems.org"
+
+gem "solargraph", group: :development
+
+gem "rdoc", "~> 6.5"
+
+gem "rubocop", "~> 1.56"

Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    ast (2.4.2)
+    backport (1.2.0)
+    base64 (0.1.1)
+    benchmark (0.2.1)
+    diff-lcs (1.5.0)
+    e2mmap (0.1.0)
+    jaro_winkler (1.5.6)
+    json (2.6.3)
+    kramdown (2.4.0)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    language_server-protocol (3.17.0.3)
+    nokogiri (1.15.4-arm64-darwin)
+      racc (~> 1.4)
+    parallel (1.23.0)
+    parser (3.2.2.3)
+      ast (~> 2.4.1)
+      racc
+    psych (5.1.0)
+      stringio
+    racc (1.7.1)
+    rainbow (3.1.1)
+    rbs (2.8.4)
+    rdoc (6.5.0)
+      psych (>= 4.0.0)
+    regexp_parser (2.8.1)
+    reverse_markdown (2.1.1)
+      nokogiri
+    rexml (3.2.6)
+    rubocop (1.56.3)
+      base64 (~> 0.1.1)
+      json (~> 2.3)
+      language_server-protocol (>= 3.17.0)
+      parallel (~> 1.10)
+      parser (>= 3.2.2.3)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.28.1, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 3.0)
+    rubocop-ast (1.29.0)
+      parser (>= 3.2.1.0)
+    ruby-progressbar (1.13.0)
+    solargraph (0.49.0)
+      backport (~> 1.2)
+      benchmark
+      bundler (~> 2.0)
+      diff-lcs (~> 1.4)
+      e2mmap
+      jaro_winkler (~> 1.5)
+      kramdown (~> 2.3)
+      kramdown-parser-gfm (~> 1.1)
+      parser (~> 3.0)
+      rbs (~> 2.0)
+      reverse_markdown (~> 2.0)
+      rubocop (~> 1.38)
+      thor (~> 1.0)
+      tilt (~> 2.0)
+      yard (~> 0.9, >= 0.9.24)
+    stringio (3.0.8)
+    thor (1.2.2)
+    tilt (2.3.0)
+    unicode-display_width (2.4.2)
+    yard (0.9.34)
+
+PLATFORMS
+  arm64-darwin-22
+
+DEPENDENCIES
+  rdoc (~> 6.5)
+  rubocop (~> 1.56)
+  solargraph
+
+BUNDLED WITH
+   2.4.10

Rakefile

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+require "rdoc/task"
+task default: [:rdoc]
+
+Rake::RDocTask.new do |rdoc|
+  rdoc.rdoc_dir = "rdoc"
+  rdoc.title = "rdoc"
+  rdoc.options << "--line-numbers" << "--inline-source"
+  rdoc.rdoc_files.include("**/*.rb")
+end

exercises/ex1.rb

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+# puts "Hello World!"
+# puts "Hello Again"
+# puts "I like typing this."
+# puts "This is fun."
+# puts "Yay! Printing."
+# puts "I'd much rather you 'not'."
+# puts 'I "said" do not touch this.'
+puts "Esther fucked my brains out"

exercises/ex10.rb

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+puts "I am 6'2\" tall." # escape double-quote inside string
+puts 'I am 6\'2" tall.' # escape single-quote inside string
+
+tabby_cat = "\tI'm tabbed in."
+persian_cat = "I'm split\non a line."
+backslash_cat = "I'm \\ a \\ cat."
+
+fat_cat = "
+I'll do a list:
+\t* Cat food
+\t* Fishies
+\t* Catnip\n\t* Grass
+"
+
+puts tabby_cat
+puts persian_cat
+puts backslash_cat
+puts fat_cat
+puts "\x10 bell"

exercises/ex11.rb

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+print "How old are you? "
+age = gets.chomp
+print "How tall are you? "
+height = gets.chomp
+print "How much do you weigh? "
+weight = gets.chomp
+
+puts "So, you're #{age} years old, #{height} tall and #{weight} heavy."

exercises/ex12.rb

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+print "Give me a number: "
+number = gets.chomp.to_i
+
+bigger = number * 100
+puts "A bigger number is #{bigger}."
+
+print "Give me another number: "
+another = gets.chomp
+number = another.to_i
+
+smaller = number / 100
+
+puts "A smaller number is #{smaller}."
+
+print "Give me some money! $"
+money = gets.chomp.to_f
+puts "You can have 10% back: $#{(money / 100 * 10).round(2)}"

exercises/ex13.rb

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+first, second, third = ARGV
+
+puts "Your first variable is: #{first}"
+puts "Your second variable is: #{second}"
+puts "Your third variable is: #{third}"
+
+puts "Do a thing"
+thing = $stdin.gets.chomp
+puts thing

exercises/ex14.rb

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+user_name = ARGV.first # gets the first argument
+prompt = "> "
+
+puts "Hi #{user_name}"
+puts "I'd like to ask you a few questions."
+puts "Do you like me #{user_name}? "
+puts prompt
+likes = $stdin.gets.chomp
+
+puts "Where do you live #{user_name}? "
+puts prompt
+lives = $stdin.gets.chomp
+
+# a comma for puts is like using it twice
+puts "What kind of computer do you have? ", prompt
+computer = $stdin.gets.chomp
+
+puts "
+Alright, so you said #{likes} about liking me.
+You live in #{lives}. Not sure where that is.
+And you have a #{computer} computer. Nice.
+"

exercises/ex15/ex15.rb

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+filename = ARGV.first
+
+txt = open(filename)
+
+puts "Here's your file #{filename}:"
+print txt.read
+
+print "Type the filename again: "
+file_again = $stdin.gets.chomp
+
+txt_again = open(file_again)
+
+print txt_again.read
+
+txt.close
+txt_again.close

exercises/ex15/ex15_sample.txt

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+This is stuff I typed into a file.
+It is really cool stuff.
+Lots and lots of fun to have in here.

exercises/ex17/ex17.rb

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+from_file, to_file = ARGV
+PAD = 5
+str = "#{" " * PAD}Copying from #{from_file} to #{to_file}#{" " * PAD}"
+puts "\e[48;5;139;233;253m#{" " * str.length}\e[0m"
+puts "\e[48;5;139;233;253m#{str}\e[0m"
+puts "\e[48;5;139;233;253m#{" " * str.length}\e[0m"
+
+in_file = open(from_file)
+indata = in_file.read
+out_file = open(to_file, "w")
+out_file.write(indata)
+
+out_file.close
+in_file.close

exercises/ex17/ex17_from.txt

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+poo
+poooooo
+	poooo
+	pooo
+		poooooo!!!!

exercises/ex17/ex17_to.txt

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+poo
+poooooo
+	poooo
+	pooo
+		poooooo!!!!

exercises/ex18.rb

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+# this one is like your scripts with ARGV
+def print_two(*args)
+  arg1, arg2 = args
+  puts "arg1: #{arg1}, arg2: #{arg2}"
+end
+
+# ok, that *args is actually pointless, we can just do this
+def print_two_again(arg1, arg2)
+  puts "arg1: #{arg1}, arg2: #{arg2}"
+end
+
+# this just takes one argument
+def print_one(arg1)
+  puts "arg1: #{arg1}"
+end
+
+# this one takes no arguments
+def print_none
+  puts "I got nothin'."
+end
+
+print_two("Zed", "Shaw")
+print_two_again("Zed", "Shaw")
+print_one("First!")
+print_none

exercises/ex19.rb

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+def cheese_and_crackers(cheese_count, boxes_of_crackers)
+  puts "You have #{cheese_count} cheeses!"
+  puts "You have #{boxes_of_crackers} boxes of crackers!"
+  puts "Man that's enough for a party!"
+  puts "Get a blanket.\n"
+end
+
+puts "We can just give the function numbers directly:"
+cheese_and_crackers(20, 30)
+
+puts "OR, we can use variables from our script:"
+amount_of_cheese = 10
+amount_of_crackers = 50
+
+cheese_and_crackers(amount_of_cheese, amount_of_crackers)
+
+puts "We can even do math inside too:"
+cheese_and_crackers(10 + 20, 5 + 6)
+
+puts "And we can combine the two, variables and math:"
+cheese_and_crackers(amount_of_cheese + 100, amount_of_crackers + 1000)

exercises/ex2.rb

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+# A comment, this is so you can read your program later.
+# Anything after the # is ignored by ruby.
+
+puts "I could have code like this." # and the comment after is ignored
+
+# You can also use a comment to "disable" or comment out a piece of code
+# puts "This won't run."
+
+puts "This will run."

exercises/ex20/ex20.rb

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+input_file = ARGV.first
+
+def print_all(f)
+  puts f.read
+end
+
+def rewind(f)
+  f.seek(0)
+end
+
+def print_a_line(line_count, f)
+  puts "#{line_count}, #{f.gets.chomp}"
+end
+
+current_file = open(input_file)
+
+puts "First let's print the whole fine:\n"
+
+print_all(current_file)
+
+puts "Now let's rewind, kind of like a tape."
+
+rewind(current_file)
+
+puts "Let's print three lines:"
+
+current_line = 1
+print_a_line(current_line, current_file)
+current_line += 1
+print_a_line(current_line, current_file)
+current_line += 1
+print_a_line(current_line, current_file)

exercises/ex20/ex20_input.txt

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+Meowwww in the middle of the night i crawl onto your chest and purr gently to help you sleep
+Leave buried treasure in the sandbox for the toddlers prow?? ew dog you drink from the toilet, yum yum warm milk hotter pls, ouch too hot or lick the plastic bag yet i'm bored inside, let me out i'm lonely outside, let me in i can't make up my mind whether to go in or out, guess i'll just stand partway in and partway out, contemplating the universe for half an hour how dare you nudge me with your foot?!?! leap into the air in greatest offense!.
+Meow all night having their mate disturbing sleeping humans hiss at vacuum cleaner oooo! dangly balls! jump swat swing flies so sweetly to the floor crash move on wash belly nap and what a cat-ass-trophy! yet cats woo and stare out the window. Poop on couch

exercises/ex21.rb

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+def add(a, b)
+  puts "Adding #{a} + #{b}"
+  a + b
+end
+
+def subtract(a, b)
+  puts "Subtracting #{a} - #{b}"
+  a - b
+end
+
+def multiply(a, b)
+  puts "Multiplying #{a} * #{b}"
+  a * b
+end
+
+def divide(a, b)
+  puts "Dividing #{a} / #{b}"
+  a / b
+end
+
+puts "Let's do some math with just functions!"
+
+age = add(30, 5)
+height = subtract(78, 4)
+weight = multiply(90, 2)
+iq = divide(100, 2)
+
+puts "Age: #{age}, Height: #{height}, Weight: #{weight}, IQ: #{iq}"
+
+# A puzzle for the extra credit, type it in anyway.
+puts "Here is a puzzle."
+
+what = add(age, subtract(height, multiply(weight, divide(iq, 2))))
+puts "That becomes: #{what}. Can you do it by hand?"

exercises/ex24.rb

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+puts "Let's practice everything."
+puts "You'd need to know 'bout escapes with \\ that do \n newlines and \t tabs."
+
+# the <<END is a "heredoc". See the Student Questions
+poem = <<~END
+  \tThe lovely world
+  with logic so firmly planted
+  cannot discern \n the needs of love
+  nor comprehend passion from intuition
+  and requires an explanation
+  \n\t\twhere there is none.
+END
+
+puts "-" * 10
+puts poem
+puts "-" * 10
+
+five = 10 - 2 + 3 - 6
+puts "This should be five: #{five}"
+
+def secret_formula(started)
+  jelly_beans = started * 500
+  jars = jelly_beans / 1000
+  crates = jars / 100
+
+  [jelly_beans, jars, crates]
+end
+
+start_point = 10_000
+beans, jars, crates = secret_formula(start_point)
+
+puts "With a starting point of: #{start_point}"
+puts "We'd have #{beans} beans, #{jars} jars, and #{crates} crates."
+
+start_point /= 10
+puts "We can also do that this way:"
+puts "We'd have %s, %d jars, and %d crates." % secret_formula(start_point)

exercises/ex25.rb

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+module Ex25
+  # This function will break up words for us.
+  def self.break_words(stuff)
+    stuff.split(" ")
+  end
+
+  # Sorts the words.
+  def self.sort_words(words)
+    words.sort
+  end
+
+  def self.print_first_word(words)
+    word = words.shift
+    puts word
+  end
+
+  # Prints the last word after popping it off.
+  def self.print_last_word(words)
+    word = words.pop
+    puts word
+  end
+
+  # Takes in a full sentence and returns the sorted words.
+  def self.sort_sentence(sentence)
+    words = Ex25.break_words(sentence)
+    Ex25.sort_words(words)
+  end
+
+  # Prints the first and last words of the sentence.
+  def self.print_first_and_last(sentence)
+    words = Ex25.break_words(sentence)
+    Ex25.print_first_word(words)
+    Ex25.print_last_word(words)
+  end
+
+  # Sorts the words then prints the first and last one.
+  def self.print_first_and_last_sorted(sentence)
+    words = Ex25.sort_sentence(sentence)
+    Ex25.print_first_word(words)
+    Ex25.print_last_word(words)
+  end
+end

exercises/ex26.rb

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+module Ex25
+  # This function will break up words for us.
+  def self.break_words(stuff)
+    stuff.split(" ")
+  end
+
+  # Sorts the words.
+  def self.sort_words(words)
+    words.sort
+  end
+
+  # Prints the first word after shifting it off.
+  def self.print_first_word(words)
+    word = words.shift
+    puts word
+  end
+
+  # Prints the last word after popping it off.
+  def self.print_last_word(words)
+    word = words.pop
+    puts word
+  end
+
+  # Takes in a full sentence and returns the sorted words.
+  def self.sort_sentence(sentence)
+    words = Ex25.break_words(sentence)
+    Ex25.sort_words(words)
+  end
+
+  # Prints the first and last words of the sentence.
+  def self.print_first_and_last(sentence)
+    words = Ex25.break_words(sentence)
+    Ex25.print_first_word(words)
+    Ex25.print_last_word(words)
+  end
+
+  # Sorts the words then prints the first and last one.
+  def self.print_first_and_last_sorted(sentence)
+    words = Ex25.sort_sentence(sentence)
+    Ex25.print_first_word(words)
+    Ex25.print_last_word(words)
+  end
+end
+
+puts "Let's practice everything."
+puts 'You\'d need to know \'bout escapes with \\ that do \n newlines and \t tabs.'
+
+poem = <<~END
+  \tThe lovely world
+  with logic so firmly planted
+  cannot discern \n the needs of love
+  nor comprehend passion from intuition
+  and requires an explanation
+  \n\t\twhere there is none.
+END
+
+puts "--------------"
+puts poem
+puts "--------------"
+
+five = 10 - 2 + 3 - 6
+puts "This should be five: #{five}"
+
+def secret_formula(started)
+  jelly_beans = started * 500
+  jars = jelly_beans / 1000
+  crates = jars / 100
+  [jelly_beans, jars, crates]
+end
+
+start_point = 10000
+beans, jars, crates = secret_formula(start_point)
+
+puts "With a starting point of: #{start_point}"
+puts "We'd have #{beans} beans, #{jars} jars, and #{crates} crates."
+
+sentence = "All good things come to those who wait."
+words = Ex25.break_words(sentence)
+sorted_words = Ex25.sort_words(words)
+Ex25.print_first_word(words)
+Ex25.print_last_word(words)
+Ex25.print_first_word(sorted_words)
+Ex25.print_last_word(sorted_words)
+Ex25.sort_sentence(sentence)
+Ex25.print_first_and_last(sentence)
+Ex25.print_first_and_last_sorted(sentence)

exercises/ex28.rb

@@ -0,0 +1,16 @@
+true && true # true
+false && true # false
+1 == 1 && 2 == 1 # false # true
+1 == 1 || 2 != 1 # true
+true && 1 == 1 # true
+false && 0 != 0 # false
+true || 1 == 1 # true # false
+1 != 0 && 2 == 1 # true # true # false
+(true && false) # true
+(1 == 1 && 0 != 1) # false
+(10 == 1 || 1000 == 1000) # false
+(1 != 10 || 3 == 4) # false
+("testing" == "testing" && "Zed" == "Cool Guy") # true
+1 == 1 && !("testing" == 1 || 1 == 0) # true
+"chunky" == "bacon" && !(3 == 4 || 3 == 3) # false
+3 == 3 && !("testing" == "testing" || "Ruby" == "Fun") # false

exercises/ex29.rb

@@ -0,0 +1,33 @@
+people = 20
+cats = 30
+dogs = 15
+
+if people < cats
+  puts "Too many cats! The world is doomed!"
+end
+
+if people > cats
+  puts "Not many cats! The world is saved!"
+end
+
+if people < dogs
+  puts "The world is drooled one!"
+end
+
+if people > dogs
+  puts "The world is dry!"
+end
+
+dogs += 5
+
+if people >= dogs
+  puts "People are greater than or equal to dogs."
+end
+
+if people <= dogs
+  puts "People are less than or equal to dogs."
+end
+
+if people == dogs
+  puts "People are dogs."
+end

exercises/ex3.rb

@@ -0,0 +1,23 @@
+puts "I will now count my chickens:"
+
+puts "Hens #{25 + 30 / 6}"
+puts "Roosters #{100 - 25 * 3 % 4}"
+
+puts "Now I will count the eggs:"
+
+puts 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6
+
+puts "Is it true that 3 + 1 < 5 - 7?"
+
+puts 3 + 2 < 5 - 7
+
+puts "What is 3 + 2? #{3 + 2}"
+puts "What is 5 - 7? #{5 - 7}"
+
+puts "Oh, that's why it's false."
+
+puts "How about some more."
+
+puts "Is it greater? #{5 > -2}"
+puts "Is it greater or equal? #{5 >= -2}"
+puts "Is it less or equal? #{5 <= 2}"

exercises/ex30.rb

@@ -0,0 +1,25 @@
+people = 30
+cars = 40
+trucks = 15
+
+if cars > people
+  puts "We should take the cars."
+elsif cars < people
+  puts "We should not take the cars."
+else
+  puts "We can't decided."
+end
+
+if trucks > cars
+  puts "That's too many trucks."
+elsif trucks < cars
+  puts "Maybe we could take the trucks."
+else
+  puts "We still can't decide."
+end
+
+if people > trucks
+  puts "Alright, let's just take the trucks."
+else
+  puts "Fine, let's stay home then."
+end

exercises/ex31.rb

@@ -0,0 +1,39 @@
+puts "You enter a dark room with two doors. Do you go through door #1 or door #2?"
+
+print "> "
+door = $stdin.gets.chomp
+
+if door == "1"
+  puts "There's a giant bear here eating a cheese cake. What do you do?"
+  puts "1. Take the cake."
+  puts "2. Scream at the bear."
+
+  print "> "
+  bear = $stdin.gets.chomp
+
+  if bear == "1"
+    puts "The bear eats your face off. Good job!"
+  elsif bear == "2"
+    puts "The bear eats your legs off. Good job!"
+  else
+    puts "Well, doing %s is probably better. Bear runs away." % bear
+  end
+
+elsif door == "2"
+  puts "You stare into the endless abyss at Cthulhus's retina."
+  puts "1. Blueberries."
+  puts "2. Yellow jacket clothespins."
+  puts "3. Understanding revolvers yelling melodies."
+
+  print "> "
+  insanity = $stdin.gets.chomp
+
+  if insanity == "1" || insanity == "2"
+    puts "Your body survives powered by a mind of jello. Good job!"
+  else
+    puts "The insanity rots your eyes into a pool of muck. Good job!"
+  end
+
+else
+  puts "You stumble around and fall on a knife and die. Good job!"
+end

exercises/ex32.rb

@@ -0,0 +1,37 @@
+the_count = [1, 2, 3, 4, 5]
+fruits = ["apples", "oranges", "pears", "apricots"]
+change = [1, "pennies", 2, "dimes", 3, "quarters"]
+
+# this first kind of for-loop goes through a list
+# in a more traditional style found in other languages
+# for number in the_count
+#   puts "This is count #{number}"
+# end
+the_count.each do |number|
+  puts "This is count #{number}"
+end
+
+# same as above, but in a more Ruby style
+# this and the next one are the preferred
+# way Ruby for-loops are written
+fruits.each do |fruit|
+  puts "A fruit of type: #{fruit}"
+end
+
+# also we can go through mixed lists too
+# note this is yet another style, exactly like above
+# but a different syntax (way to write it).
+change.each { |i| puts "I got #{i}" }
+
+# we can also build lists, first start with an empty one
+elements = []
+
+# then use the range operator to do 0 to 5 counts
+6.times do |i|
+  puts "adding #{i} to the list."
+  # pushes the i variable on the *end* of the list
+  elements.push(i)
+end
+
+# now we can print the out too
+elements.each { |i| puts "Element was: #{i}" }

exercises/ex33.rb

@@ -0,0 +1,19 @@
+def generate_numbers(max, inc)
+  numbers = []
+  (0..max - 1).step(inc) do |i|
+    puts "At the top i is #{i}"
+    numbers.push(i)
+
+    puts "Numbers now: ", numbers
+    puts "At the bottom i is #{i}"
+  end
+
+  numbers
+end
+
+numbers = generate_numbers(10, 2)
+
+puts "The numbers: "
+numbers.each do |number|
+  puts number
+end

exercises/ex35.rb

@@ -0,0 +1,86 @@
+def gold_room
+  puts "This room is full of gold. How much do you take?"
+
+  print "> "
+  choice = $stdin.gets.chomp
+
+  if /\d+/.match?(choice)
+    how_much = choice.to_i
+  else
+    dead("Man, learn to types a number.")
+  end
+
+  if how_much < 50
+    puts "Nice, you're not greedy, you win!"
+    exit(0)
+  else
+    dead("You greedy bastard!")
+  end
+end
+
+def bear_room
+  puts "There is a bear here."
+  puts "The bear has a bunch of honey."
+  puts "The fat bear is in front of another door."
+  puts "How are you going to move the bear?"
+  bear_moved = false
+
+  loop do
+    print ">"
+    choice = $stdin.gets.chomp
+
+    if choice == "take honey"
+      dead("The bear looks at you then slaps your face off.")
+    elsif choice == "taunt bear" && !bear_moved
+      puts "The bear has moved from the door. You can go through it now."
+      bear_moved = true
+    elsif choice == "taunt bear" && bear_moved
+      dead("The bear gets pissed of and chews your leg off.")
+    elsif choice == "open door" && bear_moved
+      gold_room
+    else
+      puts "I got no idea what that means."
+    end
+  end
+end
+
+def cthulhu_room
+  puts "Here you see the great evil Cthulhu."
+  puts "He, it, whatever stares at you and you go insane."
+  puts "Do you flee for your life or eat your head?"
+
+  print "> "
+  choice = $stdin.gets.chomp
+
+  if choice.include? "flee"
+    start
+  elsif choice.include? "head"
+    dead("Well that was tasty!")
+  else
+    cthulhu_room
+  end
+end
+
+def dead(why)
+  puts why, "Good job!"
+  exit(0)
+end
+
+def start
+  puts "You are in a dark room."
+  puts "There is a door to your right and left."
+  puts "Which one do you take?"
+
+  print "> "
+  choice = $stdin.gets.chomp
+
+  if choice == "left"
+    bear_room
+  elsif choice == "right"
+    cthulhu_room
+  else
+    dead("You stumble around the room until you starve.")
+  end
+end
+
+start

exercises/ex38.rb

@@ -0,0 +1,25 @@
+ten_things = "Apples Oranges Crows Telephone Light Sugar"
+
+puts "Wait there are not 10 things in that list. Let's fix that."
+
+stuff = ten_things.split(" ")
+more_stuff = ["Day", "Night", "Song", "Frisbee", "Corn", "Banana", "Girl", "Boy"]
+
+#  using math to make sure there's 10 items
+
+while stuff.length != 10
+  next_one = more_stuff.pop
+  puts "Adding: #{next_one}"
+  stuff.push(next_one)
+  puts "There are #{stuff.length} items now."
+end
+
+puts "There we go: #{stuff}"
+puts "Let's do some things with stuff."
+
+puts stuff[1]
+puts stuff[-1] # whoah! fancy
+puts stuff.pop
+puts stuff.join(" ")
+puts stuff[3..5].join("#")
+puts stuff

exercises/ex39.rb

@@ -0,0 +1,55 @@
+# create a mapping of state to abbreviation
+states = {
+  "Oregon" => "OR",
+  "Florida" => "FL",
+  "California" => "CA",
+  "New York" => "NY",
+  "Michigan" => "MI"
+}
+
+# create a basic set of states and some cities in them
+cities = {
+  "CA" => "San Francisco",
+  "MI" => "Detroit",
+  "FL" => "Jacksonville"
+}
+
+# add some more cities
+cities["NY"] = "New York"
+cities["OR"] = "Portland"
+
+# puts out some cities
+puts "-" * 10
+puts "NY State has: #{cities["NY"]}"
+puts "OR State has: #{cities["OR"]}"
+
+# do it by using the state then cities dict
+puts "-" * 10
+puts "Michigan has: #{cities[states["Michigan"]]}"
+puts "Florida has: #{cities[states["Florida"]]}"
+
+# puts every city in state
+puts "-" * 10
+cities.each do |abbrev, city|
+  puts "#{abbrev} has the city #{city}"
+end
+
+# now do both at the same time
+puts "-" * 10
+states.each do |state, abbrev|
+  city = cities[abbrev]
+  puts "#{state} is abbreviated #{abbrev} and has city #{city}"
+end
+
+puts "-" * 10
+# by default ruby says "nil" when something isn't in there
+state = states["Texas"]
+
+if !state
+  puts "Sorry, no Texas."
+end
+
+# default values using ||= with the nil result
+city = cities["TX"]
+city ||= "Does not exist"
+puts "The city for state 'TX' is: #{city}"

exercises/ex4.rb

@@ -0,0 +1,15 @@
+cars = 100
+space_in_a_car = 4
+drivers = 30
+passengers = 90
+cars_not_driven = cars - drivers
+cars_driven = drivers
+carpool_capacity = cars_driven * space_in_a_car
+average_passengers_per_car = passengers / cars_driven
+
+puts "There are #{cars} cars available."
+puts "There are only #{drivers} drivers available."
+puts "There will be #{cars_not_driven} empty cars today."
+puts "We can transport #{carpool_capacity} people today."
+puts "We have #{passengers} to carpool today."
+puts "We need to put about #{average_passengers_per_car} in each car."

exercises/ex40.rb

@@ -0,0 +1,25 @@
+class Song
+  def initialize(lyrics)
+    @lyrics = lyrics
+  end
+
+  def sing_me_a_song
+    @lyrics.each do |line|
+      puts line
+    end
+  end
+end
+
+happy_bday = Song.new([
+  "Happy birthday to you",
+  "I don't want to get sued",
+  "So I'll stop right there"
+])
+
+bulls_on_parade = Song.new([
+  "They rally around tha family",
+  "With pockets full of shells"
+])
+
+happy_bday.sing_me_a_song
+bulls_on_parade.sing_me_a_song

exercises/ex41.rb

@@ -0,0 +1,97 @@
+require "open-uri"
+
+WORD_URL = "http://learncodethehardway.org/words.txt"
+WORDS = []
+
+PHRASES = {
+  "class ### < ###\nend" =>
+       "Make a class named ### that is-a ###.",
+  "class ###\n\tdef initialize(@@@)\n\tend\nend" =>
+       "class ### has-a initialize that takes @@@ parameters.",
+  "class ###\n\tdef ***(@@@)\n\tend\nend" =>
+       "class ### has-a function named *** that takes @@@ parameters.",
+  "*** = ###.new()" =>
+       "Set *** to an instance of class ###.",
+  "***.***(@@@)" =>
+       "From *** get the *** function, and call it with parameters @@@.",
+  "***.*** = '***'" =>
+       "From *** get the *** attribute and set it to '***'."
+}
+
+PHRASE_FIRST = ARGV[0] == "english"
+
+URI.open(WORD_URL) { |f|
+  f.each_line do |word|
+    WORDS.push(word.chomp)
+  end
+}
+
+def craft_names(rand_words, snippet, pattern, caps = false)
+  names = snippet.scan(pattern).map do
+    word = rand_words.pop
+    caps ? word.capitalize : word
+  end
+
+  names * 2
+end
+
+def craft_params(rand_words, snippet, pattern)
+  names = (0...snippet.scan(pattern).length).map do
+    param_count = rand(1..3)
+    params = (0...param_count).map do |x|
+      rand_words.pop
+    end
+    params.join(", ")
+  end
+
+  names * 2
+end
+
+def convert(snippet, phrase)
+  rand_words = WORDS.sort_by { rand }
+  class_names = craft_names(rand_words, snippet, /###/, caps = true)
+  other_names = craft_names(rand_words, snippet, /\*\*\*/)
+  param_names = craft_params(rand_words, snippet, /@@@/)
+
+  results = []
+
+  [snippet, phrase].each do |sentence|
+    # fake class names, also copies sentence
+    result = sentence.gsub("###") do |x|
+      class_names.pop
+    end
+
+    # fake other names
+    result.gsub!("***") do |x|
+      other_names.pop
+    end
+
+    # fake parameter lists
+    result.gsub!(/@@@/) do |x|
+      param_names.pop
+    end
+
+    results.push(result)
+  end
+
+  results
+end
+
+# keep going until they hit CTRL-D
+loop do
+  snippets = PHRASES.keys.sort_by { rand }
+
+  snippets.each do |snippet|
+    phrase = PHRASES[snippet]
+    question, answer = convert(snippet, phrase)
+
+    if PHRASE_FIRST
+      question, answer = answer, question
+    end
+
+    print question, "\n\n> "
+    exit(0) unless $stdin.gets
+
+    puts "\nANSWER: %s\n\n" % answer
+  end
+end

exercises/ex42.rb

@@ -0,0 +1,102 @@
+# Animal is-a object
+class Animal
+  def initialize(latin_name)
+    # Animal has-a latin_name
+    @latin_name = latin_name
+  end
+end
+
+# Dog is-a Animal
+class Dog < Animal
+  def initialize(latin_name, name)
+    super(latin_name)
+    # Dog has-a name
+    @name = name
+  end
+end
+
+# Cat is-a Animal
+class Cat < Animal
+  def initialize(latin_name, name)
+    super(latin_name)
+    # Cat has-a name
+    @name = name
+  end
+
+  attr_reader :name
+end
+
+# Person is-a object
+class Person
+  def initialize(name, pet = nil)
+    # Person has-a name
+    @name = name
+
+    # Person has-a pet of some kind
+    @pet = pet
+  end
+
+  attr_accessor :pet
+end
+
+# Employee is-a Person
+class Employee < Person
+  def initialize(name, salary)
+    super(name)
+    @salary = salary
+  end
+end
+# class Employee < Person
+#   def initialize(name, salary)
+#     # Employee has-a name
+#     super(name)
+#     # Employee has-a salary
+#     @salary = salary
+#   end
+# end
+
+# Fish is-a object
+class Fish
+end
+
+# Salmon is-a Fish
+class Salmon < Fish
+end
+
+# Halibut is-a Fish
+class Halibut < Fish
+end
+
+# rover is-a Dog
+rover = Dog.new("Latin", "Rover")
+
+# satan is-a Cat
+satan = Cat.new("Latin", "Satan")
+
+# mary is-a Person
+mary = Person.new("Mary")
+
+# mary has-a Pet, satan
+mary.pet = satan
+
+# frank is-a Employee
+frank = Employee.new("Frank", 120_000)
+
+# frank has-a pet, rover
+frank.pet = rover
+
+# flipper is-a Fish
+flipper = Fish.new
+
+# crouse is-a Salmon
+crouse = Salmon.new
+
+# harry is-a Halibut
+harry = Halibut.new
+
+# fidget is-a cat
+fidget = Cat.new("Latin", "Fidget")
+# james is-a Person and has-a pet, Fidget
+james = Person.new("James", fidget)
+
+puts james.pet.name # Fidget

exercises/ex5.rb

@@ -0,0 +1,17 @@
+name = "Zed A. Shaw"
+age = 35 # not a lie in 2009
+height = 74 # inches
+weight = 180 # lbs
+eyes = "Blue"
+teeth = "White"
+hair = "Brown"
+
+puts "Let's talk about #{name}"
+puts "He's #{height} inches tall."
+puts "He's #{weight} pounds heavy."
+puts "Actually that's not too heavy."
+puts "He's got #{eyes} eyes and #{hair} hair."
+puts "His teeth are usually #{teeth} depending on the coffee."
+
+# this line is tricky, try to get it exactly right
+puts "If I add #{age}, #{height}, and #{weight} I get #{age + height + weight}."

exercises/ex6.rb

@@ -0,0 +1,21 @@
+types_of_people = 10
+x = "There are #{types_of_people} types of people."
+binary = "binary"
+do_not = "don't"
+y = "Those who know #{binary} and those who #{do_not}."
+
+puts x
+puts y
+
+puts "I said: #{x}."
+puts "I also said: '#{y}'."
+
+hilarious = false
+joke_evaluation = "Isn't that joke so funny?! #{hilarious}"
+
+puts joke_evaluation
+
+w = "This is the left side of..."
+e = "a string with a right side."
+
+puts w + e

exercises/ex7.rb

@@ -0,0 +1,21 @@
+puts "Mary had a little lamb."
+puts "Its fleece was white as snow."
+puts "And everywhere that Mary went."
+puts "." * 10 # what'd that do?
+
+end1 = "C"
+end2 = "h"
+end3 = "e"
+end4 = "e"
+end5 = "s"
+end6 = "e"
+end7 = "B"
+end8 = "u"
+end9 = "r"
+end10 = "g"
+end11 = "e"
+end12 = "r"
+
+# watch that print vs. puts on this line what's it do?
+print end1 + end2 + end3 + end4 + end5 + end6
+puts end7 + end8 + end9 + end10 + end11 + end12

exercises/ex8.rb

@@ -0,0 +1,14 @@
+formatter = "%<first>s %<second>s %<third>s %<fourth>s"
+
+puts format(formatter, first: 1, second: 2, third: 3, fourth: 4)
+puts format(formatter, first: "one", second: "two", third: "three", fourth: "four")
+puts format(formatter, first: true, second: false, third: true, fourth: false)
+puts format(formatter, first: formatter, second: formatter, third: formatter, fourth: formatter)
+
+puts format(
+  formatter,
+  first: "I had this thing.",
+  second: "That you could type up right.",
+  third: "But it didn't sing.",
+  fourth: "So I said goodnight."
+)

exercises/ex9.rb

@@ -0,0 +1,14 @@
+# Here's some new strange stuff, remember to type it exactly.
+
+days = "Mon Tue Wed Thu Fri Sat Sun"
+months = "Jan\nFeb\nMar\nApr\nMay\nJun\nJul\nAug"
+
+puts "Here are the days: #{days}"
+puts "Here are the months: #{months}"
+
+puts "
+There's something going on here.
+With this weird quote
+We'll be able to type as much as we like.
+Even 4 lines if we want, or 5, or 6.
+"