private HashSet <string> GetCandidates(string seed, WordDictionaryHash words)
{
WordTest wordTest = new WordTest(seed);
return(wordTest.DoTest(words[seed.Length]));
return(new HashSet <string>());
}
public List <string> ProcessChain(string start, string end, WordDictionaryHash words)
{
Queue <string> queue = new Queue <string>();
queue.Enqueue(start);
var result = FindTarget(start, end, queue, words);
return(result.Item1 ? result.Item2.ToList() : new List <string>());
}
private static async Task <WordDictionaryHash> LoadWords(string path)
{
using (var stream = new StreamReader(path))
{
WordDictionaryHash words = new WordDictionaryHash();
string line;
while ((line = await stream.ReadLineAsync()) != null)
{
words.Add(line);
}
return(words);
}
}
private Tuple <bool, Queue <string> > FindTarget(string seed, string target, Queue <string> queue, WordDictionaryHash words)
{
HashSet <string> candidates = GetCandidates(seed, words);
if (!candidates.Any())
{
return(Tuple.Create(false, queue));
}
if (candidates.Contains(target))
{
queue.Enqueue(target);
return(Tuple.Create(true, queue));
}
for (int i = 0; i < target.Length; i++)
{
var test = seed.ToCharArray();
test[i] = target[i];
if (candidates.Contains(test.ToString()))
{
candidates.Remove(test.ToString());
queue.Enqueue(test.ToString());
var result = FindTarget(test.ToString(), target, queue, words);
if (result.Item1)
{
return(result);
}
queue.Dequeue();
}
foreach (var candidate in candidates)
{
queue.Enqueue(candidate);
var result = FindTarget(test.ToString(), target, queue, words);
if (result.Item1)
{
return(result);
}
queue.Dequeue();
}
}
return(Tuple.Create(false, queue));
}
