TrieNode.cs

usingSystem;
usingSystem.Collections.Generic;

namespaceDataStructures.Trees
{
/// <summary>
/// The Trie Node.
/// </summary>
publicclassTrieNode
{
/// <summary>
/// Instance variables.
/// </summary>
publicvirtualcharKey{get;set;}
publicvirtualboolIsTerminal{get;set;}
publicvirtualTrieNodeParent{get;set;}
publicvirtualDictionary<char,TrieNode>Children{get;set;}

/// <summary>
/// CONSTRUCTORS
/// </summary>
publicTrieNode(charkey):this(key,false){}

publicTrieNode(charkey,boolisTerminal)
{
Key=key;
IsTerminal=isTerminal;
Children=newDictionary<char,TrieNode>();
}

/// <summary>
/// Return the word at this node if the node is terminal; otherwise, return null
/// </summary>
publicvirtualstringWord
{
get
{
if(!IsTerminal)
returnnull;

varcurr=this;
varstack=newStack<char>();

while(curr.Parent!=null)
{
stack.Push(curr.Key);
curr=curr.Parent;
}

returnnewString(stack.ToArray());
}

}

/// <summary>
/// Returns an enumerable list of key-value pairs of all the words that start 
/// with the prefix that maps from the root node until this node.
/// </summary>
publicvirtualIEnumerable<String>GetByPrefix()
{
if(IsTerminal)
yieldreturnWord;

foreach(varchildKeyValinChildren)
foreach(varterminalNodeinchildKeyVal.Value.GetByPrefix())
yieldreturnterminalNode;
}

/// <summary>
/// Returns an enumerable collection of terminal child nodes.
/// </summary>
publicvirtualIEnumerable<TrieNode>GetTerminalChildren()
{
foreach(varchildinChildren.Values){
if(child.IsTerminal)
yieldreturnchild;

foreach(vargrandChildinchild.GetTerminalChildren())
if(grandChild.IsTerminal)
yieldreturngrandChild;
}
}

/// <summary>
/// Remove this element upto its parent.
/// </summary>
publicvirtualvoidRemove()
{
IsTerminal=false;

if(Children.Count==0&&Parent!=null)
{
Parent.Children.Remove(Key);

if(!Parent.IsTerminal)
Parent.Remove();
}
}

/// <summary>
/// IComparer interface implementation
/// </summary>
publicintCompareTo(TrieNodeother)
{
if(other==null)
return-1;

returnthis.Key.CompareTo(other.Key);

}

/// <summary>
/// Clears this node instance
/// </summary>
publicvoidClear()
{
Children.Clear();
Children=null;
}
}
}