private void Matches(TrieNode node,
char letter,
string word,
int[] previousRow,
List<Match<string>> results,
int maxDistance)
{
var columns = word.Length + 1;
var currentRow = new List<int> { previousRow[0] + 1 };
foreach (var column in Enumerable.Range(1, columns - 1))
{
var insertCost = currentRow[column - 1] + 1;
var deleteCost = previousRow[column] + 1;
int replaceCost;
if (word[column - 1] != letter)
replaceCost = previousRow[column - 1] + 1;
else
replaceCost = previousRow[column - 1];
currentRow.Add(Math.Min(Math.Min(insertCost, deleteCost), replaceCost)); //min of 3
}
if (currentRow[currentRow.Count - 1] <= maxDistance && !string.IsNullOrEmpty(node.Word))
results.Add(new Match<string>(node.Word, currentRow[currentRow.Count - 1]));
if (currentRow.Min() <= maxDistance)
{
foreach (var child in node.Children)
Matches(child, child.Letter, word, currentRow.ToArray(), results, maxDistance);
}
}
public void Add(string word)
{
if (string.IsNullOrEmpty(word))
throw new ArgumentNullException("word");
var current = Root;
foreach (var letter in word)
{
TrieNode child;
if (!current.TryGetChildWith(letter, out child))
current.AddChild(child = new TrieNode(letter));
current = child;
}
current.Word = word;
}
public bool TryGetChildWith(char character, out TrieNode child)
{
return _children.TryGetValue(character, out child);
}
public void AddChild(TrieNode child)
{
_children.Add(child.Letter, child);
}
public Trie()
{
Root = new TrieNode('0');
}