Pull Request for Week 2 - Learn to Program

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

@@ -1,3 +1,16 @@
 def ask question
-  # your code here
+  while true
+   	puts question
+   	reply = gets.chomp.downcase
+   	if (reply == 'yes' || reply == 'no')
+   		if reply == 'yes'
+   			return true
+   		else
+   			return false
+   		end
+   		break
+   	else
+   		puts 'Please answer "yes" or "no".'
+   	end
+  end
 end

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

@@ -1,3 +1,13 @@
 def old_roman_numeral num
-  # your code here
+  puts "Oops! Try using a positive integer!" if num <= 0
+    roman = ''
+      roman << 'M' * (num / 1000)
+      roman << 'D' * (num % 1000 / 500)
+      roman << 'C' * (num % 500 / 100)
+      roman << 'L' * (num % 100 / 50)
+      roman << 'X' * (num % 50 / 10)
+      roman << 'V' * (num % 10 / 5)
+      roman << 'I' * (num % 5 / 1)
+
+  return roman
 end

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

@@ -1,3 +1,38 @@
 def roman_numeral num
-  # your code here
+  puts "Oops! Try using a positive integer!" if num <= 0
+
+  thous = (num / 1000)
+  hunds = (num % 1000 / 100)
+  tens  = (num % 100 / 10)
+  ones  = (num % 10)
+
+  roman = 'M' * thous
+
+  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 = romann + '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
+  return roman
 end

ch10-nothing-new/dictionary_sort.rb

@@ -1,3 +1,9 @@
 def dictionary_sort arr
-  # your code here
+  return arr if arr.length <= 1
+
+  middle = arr.pop
+  less = arr.select{|x| x.downcase < middle.downcase} 
+  more = arr.select{|x| x.downcase >= middle.downcase}
+
+  dictionary_sort(less) + [middle] + dictionary_sort(more)
 end

ch10-nothing-new/english_number.rb

@@ -1,3 +1,86 @@
 def english_number number
-  # your code here
-end
+  if number < 0
+      return "Oops! Please use a positive integer!"
+  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
+      # Now here's the recursion:
+      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 +1,15 @@
-# your code here
+require './ch10-nothing-new/english_number.rb'
+
+ def pluralize(num, word)
+   num == "one" ? num + " " + word : num + " " + word + "s"
+ end
+
+ count = 9999
+ while count > 0
+   number_bottles = english_number(count)
+   bottles = pluralize(number_bottles, "bottle")
+   puts "#{bottles.capitalize} of beer on the wall, #{bottles} of beer."
+   count -= 1
+   bottles = pluralize(english_number(count), "bottle")
+   puts "Take one down and pass it around, #{bottles} of beer on the wall."
+ end

ch10-nothing-new/shuffle.rb

@@ -1,3 +1,3 @@
 def shuffle arr
-  # your code here
+  arr.shuffle
 end

ch10-nothing-new/sort.rb

@@ -1,3 +1,9 @@
 def sort arr
-  # your code here
+    return arr if arr.length <= 1
+
+    middle = arr.pop
+    less = arr.select{|x| x < middle}
+    more = arr.select{|x| x >= middle}
+
+    sort(less) + [middle] + sort(more)
 end

ch11-reading-and-writing/build_a_better_playlist.rb

@@ -1,3 +1,54 @@
 def music_shuffle filenames
-  # your code here
-end
+  songs_and_paths = filenames.map do |s|
+    [s, s.split('/')] # [song, path]
+  end
+
+  tree = {:root => []}
+
+  # put each song into the tree
+  insert_into_tree = proc do |branch, song, path|
+    if path.length == 0 # add to current branch
+      branch[:root] << song
+    else # delve deeper
+      sub_branch = path[0]
+      path.shift # like "pop", but pops off the front
+
+      if !branch[sub_branch]
+        branch[sub_branch] = {:root => []}
+      end
+
+      insert_into_tree[branch[sub_branch], song, path]
+    end
+  end
+
+  songs_and_paths.each{|sp| insert_into_tree[tree, *sp]}
+
+  # recursively:
+  # - shuffle sub-branches (and root)
+  # - weight each sub-branch (and root)
+  # - merge (shuffle) these groups together
+  shuffle_branch = proc do |branch|
+    shuffled_subs = []
+
+    branch.each do |key, unshuffled|
+      shuffled_subs << if key == :root
+      unshuffled # At this level, these are all duplicates.
+      else
+        shuffle_branch[unshuffled]
+      end
+    end
+
+    weighted_songs = []
+
+    shuffled_subs.each do |shuffled_songs|
+      shuffled_songs.each_with_index do |song, idx|
+        num = shuffled_songs.length.to_f
+        weight = (idx + rand) / num
+        weighted_songs << [song, weight]
+      end
+    end
+
+    weighted_songs.sort_by{|s,v| v}.map{|s,v| s}
+  end
+  shuffle_branch[tree]
+end

ch11-reading-and-writing/build_your_own_playlist.rb

@@ -1 +1,7 @@
-# your code here
+music = Dir['**/*.mp3']
+
+File.open('playlist.m3u', 'w') do |f|
+  music.each { |song| f.write(song + "\n") }
+end
+
+puts "Finished!"

ch11-reading-and-writing/safer_picture_downloading.rb

@@ -1 +1,29 @@
-# your code here
+Dir.chdir '/This_PC/Users/Joe/Pictures'
+
+pic_names = Dir['This_PC/F:/*.jpg']
+
+puts 'What are we calling this group of snaps?'
+batch_name = gets.chomp
+puts
+print "Downloading #{pic_names.length} files: "
+
+pic_number = 1
+pic_names.each do |name|
+
+	print '.'
+	new_name = if pic_number < 0
+		"#{batch_name}0#{pic_number}.jpg"
+	else
+		"#{batch_name}#{pic_number}.jpg"
+	end
+
+	if File.exist?(new_name)
+		puts 'File name conflict. Aborting renaming process.'
+		exit
+	else
+		File.rename name, new_name
+		pic_number = pic_number + 1
+	end
+end
+    puts
+    puts 'Done and dusted!'

ch12-new-classes-of-objects/happy_birthday.rb

@@ -1 +1,18 @@
-# your code here
+puts 'What year were you born?'
+b_year = gets.chomp.to_i
+
+puts 'What month were you born? (1-12)'
+b_month = gets.chomp.to_i
+
+puts 'What day of the month were you born?'
+b_day = gets.chomp.to_i
+
+b = Time.local(b_year, b_month, b_day)
+t = Time.new
+
+age = 1
+
+while Time.local(b_year + age, b_month, b_day) <= t
+  puts 'SPANK!'
+  age = age + 1
+end

ch12-new-classes-of-objects/one_billion_seconds.rb

@@ -1 +1 @@
-# your code here
+puts(Time.gm(1993, 6, 4, 10, 31) + 10**9)

ch12-new-classes-of-objects/party_like_its_roman_to_integer_mcmxcix.rb

@@ -1,3 +1,30 @@
-def roman_to_integer roman
-  # your code here
+def roman_to_integer(roman)
+
+   roman = roman.upcase
+
+   return 0 if roman == "NULLA"
+   numerals = { M: 1000,
+                D: 500,
+                C: 100,
+                L: 50,
+                X: 10,
+                V: 5,
+                I: 1 }
+
+number = 0
+previous_value = 0
+
+i = roman.length - 1
+    while i >= 0
+    value = numerals[roman[i].to_sym]
+     return "Not a valid roman numeral" if value.nil?
+       if value >= previous_value
+       number += value
+       else
+       number -= value
+       end
+     previous_value = value
+     i -= 1
+    end
+    number
 end