public void Add(string word)
{
LRUPrefixTreeNode current = _root;
foreach (var c in word.ToLower())
{
if (!current.ContainsKey(c))
{
current.Add(c, new LRUPrefixTreeNode(current, c));
}
current = current[c];
}
current.IsWord = true;
AddToMap(current);
}
private void RemoveWordFromTree(LRUPrefixTreeNode node)
{
node.IsWord = false;
while (node.Parent != null)
{
if (node.Count == 0)
{
node.Parent.Remove(node.Value);
}
else
{
return;
}
node = node.Parent;
}
}
public bool IsWord(string word)
{
LRUPrefixTreeNode current = _root;
foreach (var c in word.ToLower())
{
if (!current.ContainsKey(c))
{
return(false);
}
current = current[c];
}
if (current.IsWord)
{
MoveToFront(_map[current]);
}
return(current.IsWord);
}
public IEnumerable <string> Predict(string word)
{
List <string> words = new List <string>();
LRUPrefixTreeNode current = _root;
foreach (var c in word.ToLower())
{
if (!current.ContainsKey(c))
{
return(words);
}
current = current[c];
}
ExpandWordsFromNode(current, word.ToLower());
return(words);
void ExpandWordsFromNode(LRUPrefixTreeNode node, string prefix)
{
if (node.IsWord)
{
words.Add(prefix);
MoveToFront(_map[node]);
}
if (node.Count == 0)
{
return;
}
foreach (var subC in node.Keys)
{
ExpandWordsFromNode(node[subC], prefix + subC);
}
}
}
private void AddToMap(LRUPrefixTreeNode node)
{
if (_map.ContainsKey(node))
{
MoveToFront(_map[node]);
}
else
{
var mapNode = new LRUPrefixTreeMapNode(node);
if (_tail != null)
{
RemoveLRU();
}
else
{
_tail = mapNode;
}
MoveToFront(mapNode);
_map.Add(node, mapNode);
}
}
internal LRUPrefixTreeMapNode(LRUPrefixTreeNode value)
{
Value = value;
}
public LRUPrefixTree(int capacity)
{
_capacity = capacity;
_map = new Dictionary <LRUPrefixTreeNode, LRUPrefixTreeMapNode>(capacity);
_root = new LRUPrefixTreeNode(null);
}
