Challenge Instructions
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Science Student Success Centre
Carleton <Coding> Challenge
4 - 9PM, January 31st, 2018
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<Purpose> The final goal for this coding challenge is to create an Android app for a
simple anagram game.
●The game provides the user with a word from the dictionary.
●The user tries to create as many words as possible that contain all the letters of the given
word plus one additional letter. Note that adding the extra letter at the beginning or the end
without reordering the other letters is not valid. For example, if the game picks the word
'ore' as a starter, the user might guess 'rose' or 'zero' but not 'sore'.
●The user can give up and see the words that they did not guess.
<How It Works> The problem will be described in an iterative approach so you will
need to complete one milestone before moving on to the next.
<Starter Code> We have provided some starter code that contains a 10 000 word
dictionary and handles the UI portions of the game. You are responsible for the actual
implementation! In order to ensure that the game is not too difficult, the computer will only
propose words that have at least 5 possible valid anagrams.
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Starter Code Explanation:
●AnagramsActivity: The starter code implements several methods:
○onCreate: this method gets called by the system when the app is launched. It is
made up of some boilerplate code plus code that opens the word list to initialize the
dictionary and code to connect the text box to the processWord helper.
○processWord: A helper that adds words to the UI and colors them.
○onCreateOptionsMenu: boilerplate
○onOptionsItemSelected: boilerplate
○defaultAction: This is the handler that is called when the floating button is clicked.
Depending on the game mode, it either starts the game or shows the missing answer
to the previous game.
●AnagramDictionary: This class will store the valid words from the text file and handle
selecting and checking words for the game. This is where your code will among the following
methods:
○AnagramDictionary: The constructor. It should store the words in the appropriate
data structures
○isGoodWord: Asserts that the given word is in the dictionary and isn't formed by
adding a letter to the start or end of the base word.
○getAnagrams: Creates a list of all possible anagrams of a given word.
○getAnagramsWithOneMoreLetter: Creates a list of all possible words that can be
formed by adding one letter to the given word.
○pickGoodStarterWord: Randomly selects a word with at least the desired number of
anagrams.
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THE CHALLENGE:
MILESTONE 1
This first section involves having a simplified version of the game where the user guesses anagrams
of the given word.
TASKS:
1. Advance the implementation of the AnagramDictionary’s constructor. Each word that is read
from the dictionary file should be stored in an ArrayList (called wordList). We will store
duplicates of our words in some other convenient data structures later but wordList will do
for now.
2. Implement getAnagrams which takes a string and finds all the anagrams of that string in our
input (Hint: Create a helper function that takes a sorts the characters of a string into
alphabetical order, e.g. "post" -> "opst").
3. You will need to create two new data structures in the constructor to make the game more
efficient. The constructor should have a HashSet that will allow you to rapidly verify whether
a user inputted word is a valid anagram. You should also group anagrams (via a HashMap)
together for easy searching (e.g key: "opst" value: ["post", "spot", "pots", "tops", ...]).
As you process the input words, check whether your HashMap already contains an entry for
that key. If it does, add the current word to the ArrayList at that key. Otherwise, create a new
ArrayList, add the word to it and store it in the HashMap with the corresponding key.
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MILESTONE 2
Milestone 2 is all about ensuring that the words picked are suitable for the anagram game.
TASKS:
1. Your task is to implement isGoodWord which checks: the provided word is a valid dictionary
word, and the word does not contain the base word as a substring.
Example: With base word “post”:
Input
Output
isGoodWord("nonstop")
true
isGoodWord("poster")
false
isGoodWord("lamp post")
false
isGoodWord("spots")
true
isGoodWord("apostrophe")
false
2. Next, implement getAnagramsWithOneMoreLetter which takes a string and finds all anagrams
that can be formed by adding one letter to that word. (You’ll need to update defaultAction in
AnagramsActivity to invoke getAnagramsWithOneMoreLetter instead of getAnagrams).
3. Now, it’s time to implement pickGoodStarterWord to make the game more interesting. Pick a
random starting point in the wordList array and check each word in the array until you find one that
has at least MIN_NUM_ANAGRAMS anagrams.
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MILESTONE 3
1. At this point, the game is functional but can be quite hard to play if you start off with a long
base word. To avoid this, let's refactor AnagramDictionary to give words of increasing length.
Your first word should be 4 letters, then 5, then 6, etc., until you reach the maximum word
length. Then reset to 4.
2. Now you have a complete game, so it’s time to extend. Be creative and add some cool
functionality! If you can’t think of anything, you can try: Two-letter mode - switch to allowing
the user to add two letters to form anagrams.
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