public int ladderLength(String beginWord, String endWord, List<String> wordList) {
    Queue<String> queue = new LinkedList<>();
    Set<String> visited = new HashSet<>();
    queue.offer(beginWord);
    int dist = 1;

    while (!queue.isEmpty()) {
        int size = queue.size();
        for (int i = 0; i < size; i++) {
            String current = queue.poll();
            if (current.equals(endWord)) {
                return dist;
            }
            for (String word : wordList) {
                if (!visited.contains(word) && canForm(word, current)) {
                    queue.offer(word);
                    visited.add(word);
                }
            }
        }
        dist++;
    }
    return -1;
}

private boolean canForm(String word, String current) {
    if (word.length() != current.length()) {
        return false;
    }
    
    int diff = 0;
    for (int i = 0; i < word.length(); i++) {
        if (word.charAt(i) != current.charAt(i)) {
            diff++;
            if (diff > 1) {
                return false;
            }
        }
    }
    return diff == 1;
}