Word Ladder and Anagrams in Java

Word Ladder: This program aims to find the shortest path possible from the start word to the end word (eg: cat to bug -> cat > cut > but > bug ) which are both input by the user 
in the command line itself using  a Breadth-First-Search. We used a queue implemented through a linked list *, a HashSet, and a HashMap. 
The HashSet setOfWords stores all words from the dictionary which are of the same length as the start word and the end word.
The main method of the program deals with error cases: 1) the start and end words should be of the same length 2) the start word and end 
word should not be the same and 3) the start word and the end word should both be present in the HashSet of words. We call the 
solutionLadder method in the main method. The solutionLadder method does two things: 1) it creates a HashMap with key value pairs where 
the keys are the words from the HashSet and the values are Arraylists containing all the neighbors of the words and 2) it retrieves the
words from a queue where the word ladder is stored in backwards order and prints it out in the start-to-end order. If no such word 
ladder exists for the input words, it prints a message saying so. 
To find the neighbors of the words stored as keys in the HashMap we have a boolean method isANeighbor that returns true if two words are
neighbors (have all common letters except one) and false if two words are not neighbors. The backwards word ladder that we used in the so
lutionLadder method is created in a method hasLadder. hasLadder uses a linked list based queue called path and a HashMap called endMap. 
The path queue is used to store all the words that have been visited from the mapOfWords HashMap that was created in solutionLadder. The
endMap HashMap stores potential links between words. The endMap keys are the neighbors of the currentWord that is being looked at from 
the path queue and the values are the currentWord itself. Once the neighbor is equal to the end word entered by the user, we start 
building the backwards word ladder. Once we have finished building this, we return true. If no such word ladder could be built, we 
return false. This method hasLadder is called in solutionLadder. 

Anagrams: This program aims to find all the possible anagrams of the word input by the user (eg: anangrams for pot are opt, top, and pot).
To do this, we create a Hashmap that stores as its keys all the words in the dictionary that are of the same length as the inputWord 
and as its values the sorted versions of the key.
We have a method called sortWord to sort the letters of the word in alphabetical order. Using this method, we not only find 
the sorted versions of all the keys in the HashMap but that of the inputWord as well. In a function called anagrams, we then compare 
the values of the HashMap with the sorted version of the inputWord. If these are the same, the key of this value is an anagram of the 
inputWord and we add it to our collectionOfAnagrams ArrayList. The ArrayList is returned by this method. In the main method, we store 
the ArrayList returned by the anagrams method and print the anagrams out. If the size of this arraylist is 0, it means, the word has no 
anagrams in the dictionary and we print an appropriate output message for this situation.

* To do this, we wrote a Queue class which is based on a linked list implementation. It has the methods: enqueue (adding to the end of 
the linked list), dequeue (removing from the front of the linked list), size (returns the number of nodes in the linked list) and 
isEmpty (boolean function that checks if the linked list is empty).

COMMAND LINE SYNTAX:

To call the word ladder method the command line syntax is: java WordGameHelper ladder [startWord] [endWord]. A word ladder will be 
found from the startWord to endWord. The code prints error messages if the command line syntax is incorrect, if the start and end words 
are not the same length, if one of the words is not in the dictionary file or if the start and end words are the same. 

In order to call the anagrams method the command line syntax is: java WordGameHelper anagram [inputWord]. Anagrams will then be found 
for the inputWord. Our code will print error messages if the command line syntax is not followed or if there are no anagrams of the 
input word found in the dictionary file. 

DATA STRUCTURES USED: 

The word ladder method uses 
1) HashSet of Strings. It stores the words from the dictionary file with the same length as the start and end words of the word ladder 
2) LinkedList implementation of a queue with the front of the queue as the front of the LinkedList and the end of the queue as the end 
of the Linked List. It stores “visited words” from the HashSet of dictionary file words. The visited words include neighbors of the 
words that are being compared to the start and end word.  
3) HashMap with String keys and ArrayList values. It stores a String key that is a word with the same length as the start and end 
words, and the value which is an ArrayList of Strings that are the neighboring (one letter difference) words of the key.
4) Another LinkedList implementation of a queue with the front of the queue as the front of the LinkedList and the end of the queue as 
the end of the LinkedList. It stores Strings of the solution words in the word ladder in order from endWord to startWord. 
5) HashMap with String keys and String values. It stores a String key that is a neighbor of the String value word. These are word links 
value pairs that will potentially be part of the final word ladder. 

The anagram method uses
1) HashMap of String keys- words from the dictionary file with the same length as the inputWord, and String values- the alphabetically 
sorted versions of the keys.
2) ArrayList of Strings. It stores String anagrams of the inputWord. 


STATUS OF THE PROGRAM 

This program compiles and runs without error. Both parts of the program, the word ladder and anagram finder, work.