/// <summary>
/// This method collects all the strings that starts with the
/// given prefix
/// </summary>
/// <param name="root"></param>
/// <param name="que"></param>
/// <returns></returns>
private Queue<String> Collect(Node root , Queue<String> que)
{
if(root.value != null)
{
que.Enqueue(root.value);
}
foreach(Node c in root.letter_pointers)
{
if(c != null)
{
root = c;
Collect(root, que);
}
}
return que;
}
/// <summary>
///
/// This default constructor creates the root node
/// for the trie
/// </summary>
public Trie()
{
this.root = new Node();
}
/// <summary>
///
/// This method finds the prefix nodes for the
/// given string
/// bascially it iterates over the trie to reach a point where
/// prefix ends and distinct strings start
/// </summary>
/// <param name="root"></param>
/// <param name="prefix"></param>
/// <param name="que"></param>
/// <returns></returns>
private Queue<String> find_prefix(Node root, char [] prefix, Queue<String> que)
{
int index_for_first_letter = Convert.ToInt32(letter_indices[char.ToUpper(prefix[0])].ToString());
if (root.letter_pointers[index_for_first_letter] == null)
{
return que;
}
//Queue<String> q = new Queue<string>();
foreach(char c in prefix)
{
int index = Convert.ToInt32(letter_indices[char.ToUpper(c)].ToString());
if(root.letter_pointers[index]!=null)
{
root = root.letter_pointers[index];
}
}
return Collect(root, que);
}
/// <summary>
/// This method inserts the word
/// into tries data structure
///
/// Implementation sucessfull
/// handled all the cases
///
/// </summary>
///
private Node insert(Node root, char[] word, int index)
{
if(root == null) // Base condition
{
root = new Node();
}
if (index == word.Length) // second base condition
{
root.value = new string(word);
return root;
}
char c = word[index];
index++;
char x = char.ToUpper(c);
string temp = letter_indices[x].ToString();
// creates the new node for that char c i.e letter
root.letter_pointers[Convert.ToInt32(temp)] = insert(root.letter_pointers[Convert.ToInt32(temp)], word, index);
return root;
}
/// <summary>
///
/// Finds the word in tries
///
/// tested for two cases
/// worked fine
/// </summary>
/// <param name="root"></param>
/// <param name="word"></param>
/// <param name="index"></param>
/// <returns></returns>
private Node find(Node root, char[] word, int index)
{
if(root == null)
{
return null;
}
if(index == word.Length)
{
return root;
}
char c = word[index];
index++;
char x = char.ToUpper(c);
string temp = letter_indices[x].ToString();
return find(root.letter_pointers[Convert.ToInt32(temp)], word, index);
}