LeetCode - 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.

public int ladderLength(String start, String end, HashSet<String> dict) {
 
        if (dict.size() == 0)  
            return 0; 
 
        LinkedList<String> wordQueue = new LinkedList<String>();
        LinkedList<Integer> distanceQueue = new LinkedList<Integer>();
 
        wordQueue.add(start);
        distanceQueue.add(1);
 
 
        while(!wordQueue.isEmpty()){
            String currWord = wordQueue.pop();
            Integer currDistance = distanceQueue.pop();
 
            if(currWord.equals(end)){
                return currDistance;
            }
 
            for(int i=0; i<currWord.length(); i++){
                char[] currCharArr = currWord.toCharArray();
                for(char c='a'; c<='z'; c++){
                    currCharArr[i] = c;
 
                    String newWord = new String(currCharArr);
                    if(dict.contains(newWord)){
                        wordQueue.add(newWord);
                        distanceQueue.add(currDistance+1);
                        dict.remove(newWord);
                    }
                }
            }
        }
 
        return 0;
    }

Also refer to http://www.darrensunny.me/leetcode-word-ladder/
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