Word Ladder

	/**
	 * Given two words (start and end), and a dictionary, find the length
of
	 * shortest transformation sequence from start to end, such that:
	 * 
	 * Only one letter can be changed at a time Each intermediate word must
	 * exist in the dictionary For example,
	 * 
	 * Given: 
	 * 
	 * 		start = "hit" 
	 * 
	 * 		end = "cog" 
	 * 
	 * 		dict = ["hot","dot","dog","lot","log"]
	 * 
	 * 
	 * As one shortest transformation is 
	 * 
	 * 		"hit" -> "hot" -> "dot" -> "dog" -> "cog", 
	 * 
	 * return its length 5.
	 * 
	 * Note: Return 0 if there is no such transformation sequence. All
words
	 * have the same length. All words contain only lowercase alphabetic
	 * characters.
	 * 
	 * */