learn_to_program

ch09-writing-your-own-methods/ask.rb

@@ -1,3 +1,15 @@
 def ask question
-  # your code here
-end
+  while true
+    puts question
+    reply = gets.chomp.downcase
+
+    if reply == "yes"
+      return true
+    elsif reply == "no"
+      return false
+    end
+
+    puts "Please answer \"yes\" or \"no\"."
+  end
+  answer
+end

ch09-writing-your-own-methods/old_school_roman_numerals.rb

@@ -1,3 +1,19 @@
 def old_roman_numeral num
-  # your code here
-end
+
+  x = ""
+
+  x = x + "M" * (num / 1000)
+  x = x + "D" * (num % 1000 / 500)
+  x = x + "C" * (num % 500 / 100)
+  x = x + "L" * (num % 100 / 50)
+  x = x + "X" * (num % 50 / 10)
+  x = x + "V" * (num % 10 / 5)
+  x = x + "I" * (num % 5 / 1)
+
+  x
+
+end
+
+puts old_roman_numeral 141
+puts old_roman_numeral 3000
+puts old_roman_numeral 6

ch09-writing-your-own-methods/roman_numerals.rb

@@ -1,3 +1,44 @@
 def roman_numeral num
-  # your code here
-end
+
+  thou = (num / 1000)
+  hund = (num % 1000 / 100)
+  tens = (num % 100 / 10)
+  ones = (num % 10)
+
+  x = "M" * thou
+
+  if hund == 4
+    x = x + "CD"
+  elsif hund == 9
+    x = x + "CM"
+  else
+    x = x + "D" * (num % 1000 / 500)
+    x = x + "C" * (num % 500 / 100)
+  end
+
+  if tens == 4
+    x = x + "XL"
+  elsif tens == 9
+    x = x + "XC"
+  else
+    x = x + "L" * (num % 100 / 50)
+    x = x + "X" * (num % 50 / 10)
+  end
+
+  if ones == 4
+    x = x + "IV"
+  elsif ones == 9
+    x = x + "IX"
+  else
+    x = x + "V" * (num % 10 / 5)
+    x = x + "I" * (num % 5 / 1)
+  end
+
+  x # returns roman numeral
+end
+
+# test criteria below
+puts (roman_numeral 4)
+puts (roman_numeral 1949)
+puts (roman_numeral 2654)
+puts (roman_numeral 9)

ch10-nothing-new/dictionary_sort.rb

@@ -1,3 +1,27 @@
 def dictionary_sort arr
-  # your code here
-end
+  recursive_sort arr, []
+end
+
+def recursive_sort unsorted, sorted
+  if unsorted.length <= 0
+    return sorted
+  end
+
+  small = unsorted.pop
+
+  remain_unsorted = []
+
+  unsorted.each do | x |
+    if x.downcase < small.downcase
+      remain_unsorted.push small
+      small = x
+    else
+      remain_unsorted.push x
+    end
+  end
+
+  sorted.push small
+  recursive_sort remain_unsorted, sorted
+end
+
+puts(dictionary_sort(["beans","Eggs","Brunch","apple","Acorn","badger"]))

ch10-nothing-new/english_number.rb

@@ -1,3 +1,117 @@
 def english_number number
-  # your code here
+  if number < 0
+    return 'Please enter a number that isn\'t negative.'
+  end
+  if number == 0
+    return 'zero'
+  end
+
+    num_string = '' # String to be returned.
+
+  ones_place = ['one', 'two', 'three',
+                'four', 'five', 'six',
+                'seven', 'eight', 'nine']
+
+  tens_place = ['ten', 'twenty', 'thirty',
+                'forty', 'fifty', 'sixty',
+                'seventy', 'eighty', 'ninety']
+
+
+  teenagers = ['eleven', 'twelve', 'thirteen',
+               'fourteen', 'fifteen', 'sixteen',
+               'seventeen', 'eighteen', 'nineteen']
+
+  zillions = [['hundred', 2],
+              ['thousand', 3],
+              ['million', 6],
+              ['billion', 9],
+              ['trillion', 12],
+              ['quadrillion', 15],
+              ['quintillion', 18],
+              ['sextillion', 21],
+              ['septillion', 24],
+              ['octillion', 27],
+              ['nonillion', 30],
+              ['decillion', 33],
+              ['undecillion', 36],
+              ['duodecillion', 39],
+              ['tredecillion', 42],
+              ['quattuordecillion', 45],
+              ['quindecillion', 48],
+              ['sexdecillion', 51],
+              ['septendecillion', 54],
+              ['octodecillion', 57],
+              ['novemdecillion', 60],
+              ['vigintillion', 63],
+              ['googol', 100]]
+
+  # "left" is how much of the number we still have left to write out.
+  # "write" is the part we are writing out right now.
+    left = number
+
+  while zillions.length > 0
+    zil_pair = zillions.pop
+    zil_name = zil_pair[0]
+    zil_base = 10 ** zil_pair[1]
+    write = left/zil_base # How many zillions left?
+    left = left - write*zil_base # Subtract off those zillions.
+
+    if write > 0
+      # Recursion:
+      prefix = english_number write
+      num_string = num_string + prefix + ' ' + zil_name
+
+      if left > 0
+        # So we don't write 'two billionfifty-one'...
+        num_string = num_string + ' '
+      end
+    end
+  end
+
+  write = left/10 # How many tens left?
+  left = left - write*10 # Subtract off those tens.
+
+  if write > 0
+    if ((write == 1) and (left > 0))
+      # Since we can't write "tenty-two" instead of
+      # "twelve", we have to make a special exception for these.
+      num_string = num_string + teenagers[left-1]
+      # Since we took care of the digit in the
+      # ones place already, we have nothing left to write.
+      left = 0
+    else
+      num_string = num_string + tens_place[write-1]
+    end
+
+    if left > 0
+      # So we don't write 'sixtyfour'...
+      num_string = num_string + '-'
+    end
+  end
+
+  write = left # How many ones left to write out?
+  left = 0 # Subtract off those ones.
+
+  if write > 0
+    num_string = num_string + ones_place[write-1]
+  end
+
+  # Now we just return "num_string"...
+  num_string
 end
+
+puts english_number( 0)
+puts english_number( 9)
+puts english_number( 10)
+puts english_number( 11)
+puts english_number( 17)
+puts english_number( 32)
+puts english_number( 88)
+puts english_number( 99)
+puts english_number(100)
+puts english_number(101)
+puts english_number(234)
+puts english_number(3211)
+puts english_number(999999)
+puts english_number(1000000000000)
+puts english_number(109238745102938560129834709285360238475982374561034)

ch10-nothing-new/ninety_nine_bottles_of_beer.rb

@@ -1 +1,109 @@
-# your code here
+# English number:
+def english_number number
+  if number < 0
+    return 'Please enter a number that isn\'t negative.'
+  end
+  if number == 0
+    return 'zero'
+  end
+
+    num_string = ''
+
+  ones_place = ['one', 'two', 'three',
+                'four', 'five', 'six',
+                'seven', 'eight', 'nine']
+
+  tens_place = ['ten', 'twenty', 'thirty',
+                'forty', 'fifty', 'sixty',
+                'seventy', 'eighty', 'ninety']
+
+
+  teenagers = ['eleven', 'twelve', 'thirteen',
+               'fourteen', 'fifteen', 'sixteen',
+               'seventeen', 'eighteen', 'nineteen']
+
+  zillions = [['hundred', 2],
+              ['thousand', 3],
+              ['million', 6],
+              ['billion', 9],
+              ['trillion', 12],
+              ['quadrillion', 15],
+              ['quintillion', 18],
+              ['sextillion', 21],
+              ['septillion', 24],
+              ['octillion', 27],
+              ['nonillion', 30],
+              ['decillion', 33],
+              ['undecillion', 36],
+              ['duodecillion', 39],
+              ['tredecillion', 42],
+              ['quattuordecillion', 45],
+              ['quindecillion', 48],
+              ['sexdecillion', 51],
+              ['septendecillion', 54],
+              ['octodecillion', 57],
+              ['novemdecillion', 60],
+              ['vigintillion', 63],
+              ['googol', 100]]
+
+    left = number
+
+  while zillions.length > 0
+    zil_pair = zillions.pop
+    zil_name = zil_pair[0]
+    zil_base = 10 ** zil_pair[1]
+    write = left/zil_base
+    left = left - write*zil_base
+
+    if write > 0
+      prefix = english_number write
+      num_string = num_string + prefix + ' ' + zil_name
+
+      if left > 0
+        num_string = num_string + ' '
+      end
+    end
+  end
+
+  write = left/10
+  left = left - write*10
+
+  if write > 0
+    if ((write == 1) and (left > 0))
+      num_string = num_string + teenagers[left-1]
+      left = 0
+    else
+      num_string = num_string + tens_place[write-1]
+    end
+
+    if left > 0
+      num_string = num_string + '-'
+    end
+  end
+
+  write = left
+  left = 0
+
+  if write > 0
+    num_string = num_string + ones_place[write-1]
+  end
+
+  num_string
+end
+
+# 99 Bottles Starts Here:
+start_num = 9999
+current_num = start_num
+
+while current_num > 2
+  puts english_number(current_num).capitalize + " bottles of beer on the wall" +
+    english_number(current_num) + " bottles of beer!"
+  current_num = current_num - 1
+  puts "Take one down, pass it around, " + english_number(current_num) +
+    " bottles of beer on the wall!"
+end
+
+puts "Two bottles of beer on the wall, two bottles of beer!"
+puts "Take one down, pass it around, one bottle of beer on the wall!"
+puts "One bottle of beer on the wall, one bottle of beer!"
+puts "Take one down , pass it around, no more bottles of beer on the wall!"

ch10-nothing-new/shuffle.rb

@@ -1,3 +1,26 @@
 def shuffle arr
-  # your code here
-end
+  shuffled = []
+
+  while arr.length > 0
+    rand_index = rand(arr.length)
+    index = 0
+    new_arr = []
+
+    arr.each do |x|
+      if index == rand_index
+        shuffled.push x
+      else
+        new_arr.push x
+      end
+
+      index = index + 1
+    end
+
+    arr = new_arr
+  end
+
+  shuffled
+
+end
+
+puts(shuffle([1,2,3,4,5,6,7,8,9]))