Solutions for Session 0

Signed-off-by: Abhishek Kumar <[email protected]>

session_0/README.md

@@ -17,6 +17,8 @@ Rails. You can refer to books on programming or websites like
 
 > Read the [installation guide](/installation.md) and [setting up local
 > workspace](/essential_git.md) to get started.
+>
+> You can also read the [solution](https://github.com/IRIS-NITK/IRIS-RoR-Bootcamp-2020/pull/62) here.
 
 ## Fizz Buzz
 

session_0/fizz_buzz.rb

@@ -37,5 +37,20 @@
 # We will raise an `ArgumentError` exception to let the caller know that
 # their function arguments were incorrect.
 def fizz_buzz(n:, x: 3, y: 5)
-  raise NotImplementedError # TODO
+  raise ArgumentError if n < 0 || x <= 0 || y <= 0
+  # map construct helps us transform the contents of arrays, ranges and hash
+  (1..n).map do |i|
+    if i % x == 0 && i % y == 0
+      'FizzBuzz'
+    elsif i % x == 0
+      'Fizz'
+    elsif i % y == 0
+      'Buzz'
+    else
+      i.to_s
+    end
+  end
+  # Note ruby methods implicitly return the value of the last executed intructions
+  # In this case the modified range
+  # Read mode about it here https://cutt.ly/XjlMYhJ
 end

session_0/item.rb

@@ -6,9 +6,8 @@ class Item
     4 => 'Miscellaneous'
   }
 
-  # TODO: Store quantity
   attr_accessor :name, :price, :category_id, :discount_rate,
-    :discount_deadline
+    :discount_deadline, :quantity
 
   def initialize(name: '', price: 0, quantity: 1, category_id: 4,
                  discount_rate: 0, discount_deadline: Time.now)
@@ -23,13 +22,14 @@ def initialize(name: '', price: 0, quantity: 1, category_id: 4,
   # Returns a boolean value whether than item is discounted i.e. the
   # discount deadline has been crossed or not.
   def discounted?
-    raise NotImplementedError # TODO
+    Time.now <= discount_deadline
   end
 
   # If the item is discounted, the current price is 
   # `price * (100 - discount rate) / 100`. Otherwise, it is same as the price.
-  #
-  # TODO: Implement instance method 'current_price'
+  def current_price
+    discounted? ? price * (100 - discount_rate)/100 : price
+  end
 
   # The stock price of item is defined as product of current price and
   # quantity.
@@ -40,6 +40,22 @@ def discounted?
   #
   # Note: If there are no items for category, stock price for category
   # should be zero.
+  def stock_price
+    current_price * quantity
+  end
+
   def self.stock_price_by_category(items)
+    # .keys method returns an array containing keys of CATEGORIES hash
+    # .to_h coverts the returned keys array into hash with the array values as keys (category_id) and zero as value.
+    stock_prices = CATEGORIES.keys.to_h { |category_id| [category_id, 0] }
+
+    # We now iterate over every item in the items array
+    # more about each can be found here https://www.tutorialspoint.com/ruby/ruby_iterators.htm
+    items.each do |item|
+      # Add price of individual items to the the stock price of coresponding category_id
+      stock_prices[item.category_id] += item.stock_price
+    end
+    # implicitly return stock prices
+    stock_prices
   end
 end

session_0/word_processing.rb

@@ -2,13 +2,16 @@
 # any non-lower case alphabet (A..Z) to corresponding lower case
 # alphabet
 def lower_case(words)
-  raise NotImplementedError # TODO
+  # Equivalent to words.map { |word| word.downcase }
+  words.map(&:downcase)
 end
 
 # Similar to `lower_case`, this function modifies the array in-place
 # and does not return any value.
 def lower_case!(words)
-  raise NotImplementedError # TODO
+  # the '!' symbol, implies inplace operation
+  # it is equivalent to words = words.map(&:downcase) 
+  words.map!(&:downcase)
 end
 
 # Given a prefix and an array of words, return an array containing
@@ -18,7 +21,9 @@ def lower_case!(words)
 # words_with_prefix('apple', ['apple', 'ball', 'applesauce']) would
 # return the words 'apple' and 'applesauce'.
 def words_with_prefix(prefix, words)
-  raise NotImplementedError # TODO
+  # the select method filters a collection, keeping values that
+  # evaluate to true.
+  words.select { |word| word.start_with?(prefix) }
 end
 
 # The similarity score between two words is defined as the length of
@@ -34,11 +39,34 @@ def words_with_prefix(prefix, words)
 # The function `similarity_score` takes two words and returns the
 # similarity score (an integer).
 def similarity_score(word_1, word_2)
-  raise NotImplementedError # TODO
+  smaller_len = word_1.size < word_2.size ? word_1.size : word_2.size
+
+  # Find the first index where the words are different.
+  # If there is no such index, return the smaller length.
+  (0...smaller_len).find { |i| word_1[i] != word_2[i] } || smaller_len
 end
 
 # Given a chosen word and an array of words, return an array of word(s)
 # with the maximum similarity score in the order they appear.
 def most_similar_words(chosen_word, words)
-  raise NotImplementedError # TODO
+  max_score = 0
+  similar_words = []
+
+  words.each do |word|
+    # score of current word
+    score = similarity_score(chosen_word, word)
+
+    # if the score of current word > max_score
+    # update the max score and add word to answers array
+    if score > max_score
+      max_score = score
+      similar_words = [word]
+    # If a word has the same score as established max score append it to the answers list
+    elsif score == max_score
+      similar_words.append(word)
+    end
+  end
+
+  # return the answer using rubys implicit return feature
+  similar_words
 end