//get all words that start with the prefix "s"
public List <string> get_matches(string s)
{
Search_Node curr_node = head;
foreach (char c in s)
{
curr_node = curr_node[c];
if (null == curr_node)
{
return(null);
}
}
List <string> res = new List <string>();
foreach (int i in curr_node.pre_words)
{
res.Add(words[i]);
}
return(res);
}
public void Add(string s)
{
char last_letter = ' ';
Search_Node curr_node = head;
Search_Node last_node = head;
foreach (char c in s)
{
last_node = curr_node;
if (null == curr_node[c])
{
curr_node[c] = new Search_Node();
}
curr_node = curr_node[c];
curr_node.pre_words.Add(counter);
last_letter = c;
}
if (!last_node[last_letter].is_a_word)
{
last_node[last_letter].is_a_word = true;
words.Add(counter++, s);
}
}
public Search()
{
words = new Dictionary <int, string>();
counter = 0;
head = new Search_Node();
}