public WordGraph GetOrCreateNode(char character)
{
if (!Nodes.TryGetValue(character, out WordGraph wordGraph))
{
Nodes[character] = wordGraph = new WordGraph(Length - 1, character);
}
return(wordGraph);
}
public IEnumerable <WordCombination> FindCombinations(IEnumerable <string> words, int requestedLength)
{
var wordsArray = words.ToArray();
// Requested length = 8? We'll only keep words of length 2-6
var wordGraphsPerLength = new WordGraph[requestedLength - 3];
for (int i = 0; i < wordGraphsPerLength.Length; i++)
{
var length = i + 2;
wordGraphsPerLength[i] = new WordGraph(length, ' ');
}
WordGraph GetWordGraph(int length)
{
return(wordGraphsPerLength[length - 2]);
}
var wordsWithRequestedLength = new List <string>();
for (int wordIndex = 0; wordIndex < wordsArray.Length; wordIndex++)
{
string word = wordsArray[wordIndex].ToLower();
var wordLength = word.Length;
if (wordLength == requestedLength)
{
wordsWithRequestedLength.Add(word);
continue;
}
if (wordLength < 2 || wordLength > requestedLength - 2)
{
continue;
}
var wordGraph = GetWordGraph(wordLength);
for (var characterIndex = 0; characterIndex < wordLength; characterIndex++)
{
var character = word[characterIndex];
wordGraph = wordGraph.GetOrCreateNode(character);
}
}
var paths = new List <WordGraphPath>(8);
for (int lengthOfFirstWord = 2; lengthOfFirstWord < requestedLength - 1; lengthOfFirstWord++)
{
var lengthOfSecondWord = requestedLength - lengthOfFirstWord;
var firstWordGraph = GetWordGraph(lengthOfFirstWord);
var secondWordGraph = GetWordGraph(lengthOfSecondWord);
var path = new WordGraphPath(firstWordGraph, secondWordGraph);
paths.Add(path);
}
var combinations = new List <WordCombination>(512);
for (var w = 0; w < wordsWithRequestedLength.Count; w++)
{
var word = wordsWithRequestedLength[w];
for (var p = 0; p < paths.Count; p++)
{
var path = paths[p];
var wordCombination = path.Walk(word, requestedLength);
if (wordCombination != null)
{
combinations.Add(wordCombination);
}
}
}
return(combinations);
}
public WordGraphPath(WordGraph firstWordGraph, WordGraph secondWordGraph)
{
_firstWordGraph = firstWordGraph;
_secondWordGraph = secondWordGraph;
}
