Learn to program exercises

ask.rb

@@ -0,0 +1,13 @@
+def ask question
+  while true
+    puts question
+    reply = gets.chomp.downcase
+    if reply == 'yes'
+      return true
+    end
+    if reply == 'no'
+      return false
+    end
+end
+likes_it = ask 'Do you like eating tacos?'
+puts likes_it

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

@@ -1,3 +1,13 @@
 def ask question
-  # your code here
-end
+  while true
+    puts question
+    reply = gets.chomp.downcase
+    if reply == 'yes'
+      return true
+    end
+    if reply == 'no'
+      return false
+    end
+end
+likes_it = ask 'Do you like eating tacos?'
+puts likes_it

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

@@ -1,3 +1,12 @@
 def old_roman_numeral num
-  # your code here
-end
+  roman = ''
+roman = roman + 'M' * (num / 1000)
+roman = roman + 'D' * (num % 1000 / 500)
+roman = roman + 'C' * (num % 500 / 100)
+roman = roman + 'L' * (num % 100 / 50)
+roman = roman + 'X' * (num % 50 / 10)
+roman = roman + 'V' * (num % 10 / 5)
+roman = roman + 'I' * (num % 5 / 1)
+roman
+end
+puts (old_roman_numeral(1999))

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

@@ -1,3 +1,33 @@
 def roman_numeral num
-  # your code here
-end
+hunds = (num % 1000 / 100)
+tens = (num % 100 / 10)
+ones = (num % 10 )
+roman = 'M' * thouscode here
+if hunds == 9
+roman = roman + 'CM'
+elsif hunds == 4
+roman = roman + 'CD'
+else
+roman = roman + 'D' * (num % 1000 / 500)
+roman = roman + 'C' * (num % 500 / 100)
+end
+if tens == 9
+roman = roman + 'XC'
+elsif tens == 4
+roman = roman + 'XL'
+else
+roman = roman + 'L' * (num % 100 / 50)
+roman = roman + 'X' * (num % 50 / 10)
+end
+if ones == 9
+roman = roman + 'IX'
+elsif ones == 4
+roman = roman + 'IV'
+else
+roman = roman + 'V' * (num % 10 / 5)
+roman = roman + 'I' * (num % 5 / 1)
+end
+roman
+end
+
+puts(roman_numeral(1999))

ch10-nothing-new/dictionary_sort.rb

@@ -1,3 +1,21 @@
 def dictionary_sort arr
-  # your code here
-end
+rec_dict_sort arr, []
+end
+def rec_dict_sort unsorted, sorted
+if unsorted.length <= 0
+return sorted
+end
+
+smallest = unsorted.pop
+still_unsorted = []
+unsorted.each do |tested_object|
+if tested_object.downcase < smallest.downcase
+still_unsorted.push smallest
+smallest = tested_object
+else
+still_unsorted.push tested_object
+end
+end
+sorted.push smallest
+rec_dict_sort still_unsorted, sorted
+end

ch10-nothing-new/english_number.rb

@@ -1,3 +1,82 @@
 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 = ''
+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

ch10-nothing-new/ninety_nine_bottles_of_beer.rb

@@ -1 +1,107 @@
-# your code here
+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
+
+num_at_start = 9999
+num_now = num_at_start
+
+while num_now > 2
+
+puts english_number(num_now).capitalize + ' bottles of beer on the wall, ' +
+
+english_number(num_now) + ' bottles of beer!'
+
+num_now = num_now - 1
+
+puts 'Take one down, pass it around, ' +
+
+english_number(num_now) + ' 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 +1,19 @@
 def shuffle arr
-  # your code here
-end
+  shuf = []
+  while arr.length > 0
+    rand_index = rand(arr.length)
+    curr_index = 0
+    new_arr = []
+    arr.each do |item|
+      if curr_index == rand_index
+        shuf.push item
+      else
+        new_arr.push item
+      end
+      curr_index = curr_index + 1
+end
+arr = new_arr
+end
+shuf
+end
+puts(shuffle([1, 2, 2, 323, 53, 54, 65, 7, 47, 54, 2, 8765, 44, 23, 48, 6, 2, 32, 6]))

ch10-nothing-new/sort.rb

@@ -1,3 +1,24 @@
 def sort arr
-  # your code here
-end
+  rec_sort arr, []
+end
+
+def rec_sort unsorted, sorted
+  if unsorted.length <= 0
+    return sorted
+  end
+
+smallest = unsorted.pop
+still_unsorted = []
+
+unsorted.each do |tested_object|
+  if tested_object < smallest
+still_unsorted.push smallest
+smallest = tested_object
+else
+still_unsorted.push tested_object
+end
+end
+sorted.push smallest
+rec_sort still_unsorted, sorted
+end
+puts(sort(['hello','this','should','be','sorted','into','the','right', 'order']))

ch11-reading-and-writing/build_a_better_playlist.rb

@@ -1,3 +1,32 @@
 def music_shuffle filenames
-  # your code here
-end
+  filenames = filenames.sort
+
+  len = filenames.length
+  2.times do
+
+  l_idx = 0
+  r_idx = len/2
+  shuf = []
+  while shuf.length < len
+  if shuf.length%2 == 0
+  shuf.push(filenames[r_idx])
+  r_idx = r_idx + 1
+else
+  shuf.push(filenames[l_idx])
+  l_idx = l_idx + 1
+  end
+  end
+  filenames = shuf
+  end
+  arr = []
+  cut = rand(len)
+  idx = 0
+  while idx < len
+  arr.push(filenames[(idx+cut)%len])
+  idx = idx + 1
+  end
+  arr
+  end
+  songs = ['aa/bbb', 'aa/ccc', 'aa/ddd',
+  'AAA/xxxx', 'AAA/yyyy', 'AAA/zzzz', 'foo/bar']
+  puts(music_shuffle(songs))