//Adds the given child to the node
public Node addChild(char letter)
{
//Checks if given node has any children
//if not creates dictionary for them
if (children == null)
{
children = new Dictionary<char, Node>();
}
//Checks if the given node already has mapping for the letter
//If not, creates a mapping to it
if (!children.ContainsKey(letter))
{
//checks if letter isnt EoW letter
if (letter == endOfWord)
{
children.Add(letter, null);
return null;
}
else
{
var node = new Node(letter);
children.Add(letter, node);
return node;
}
}
//returns of a node representation of the child with the given letter
return (Node)children[letter];
}
//Private helper method to recursively call a match, in order to fetch
//all the results stemming from a given substring input
//Param node: the node being inspected, going to be branched out from
//Param allWords: the continually building set of all terminal node words
//Param currentStr: The current set of letters which is all the letters of the nodes in the path it took to get where it is
//Param substring: The substring of the possible words one is searching for
//param numResults: the max number of matches of words that one wants
private static void matchRecursive(Node node, List<string> allWords, string currentStr, string substr, int numResults)
{
//if the set has already reached the desired amount
if (allWords.Count == numResults)
{
return;
}
//if node passed is null, which happens when reached a terminal word
if (node == null)
{
//if list doesn't contain the string, add the string to it, and return
if (!allWords.Contains(currentStr))
{
allWords.Add(currentStr);
}
return;
}
//concatenate the current letters to add the given node letter
currentStr += node.letter.ToString();
//if the string isn't empty
if (substr.Length > 0)
{
//if the node has a mapping to a child with the first letter in the substring
if (node.children.ContainsKey(substr[0]))
{
//recursively call the child node, and then chop off first letter, and keep going
matchRecursive(node.children[substr[0]], allWords, currentStr, substr.Remove(0, 1), numResults);
}
}
//else substring was empty, so get all other keys associated
else
{
foreach (char key in node.children.Keys)
{
matchRecursive(node.children[key], allWords, currentStr, substr, numResults);
}
}
}
//Initilizes Tree, sets root node
public Trie()
{
root = new Node { letter = Node.root };
}