//Insert a word into the Trie. O(m) time/space complexity. m is word length
public void Insert(String word)
{
TrieArrayNode node = root;
for (int i = 0; i < word.Length; ++i)
{
if (!node.ContainsKey(word[i]))
{
node.Put(word[i], new TrieArrayNode());
}
node = node.Get(word[i]);
}
node.SetEnd();
}
//search a prefix(or whole key) in trie and
//returns the node where search ends
//O(m) time complexity, O(1) space complexity
private TrieArrayNode SearchPrefix(string prefix)
{
TrieArrayNode node = root;
for (int i = 0; i < prefix.Length; ++i)
{
if (node.ContainsKey(prefix[i]))
{
node = node.Get(prefix[i]);
}
else
{
return(null);
}
}
return(node);
}
// Returns if there is any word in the trie
// that starts with the given prefix.
// O(m) time complexity, O(1) space complexity
public bool StartsWith(string prefix)
{
TrieArrayNode node = SearchPrefix(prefix);
return(node != null);
}
//Search a whole word in the trie
//Returns if the word is in the trie.
public bool Search(String word)
{
TrieArrayNode node = SearchPrefix(word);
return(node != null && node.IsEnd());
}
//constructor
public TrieArray()
{
root = new TrieArrayNode();
}
//put a child node in
public void Put(char ch, TrieArrayNode node)
{
children[ch - 'a'] = node;
}
