Question

Does anyone know where I can find an example of how to construct a trie in C#? I’m trying to take a dictionary/list of words and create a trie with it.

Answer 1

This is my own code, pulled from my answer to How to find a word from arrays of characters? :

public class Trie
{
  public struct Letter
  {
    public const string Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    public static implicit operator Letter(char c)
    {
      return new Letter() { Index = Chars.IndexOf(c) };
    }
    public int Index;
    public char ToChar()
    {
      return Chars[Index];
    }
    public override string ToString()
    {
      return Chars[Index].ToString();
    }
  }

  public class Node
  {
    public string Word;
    public bool IsTerminal { get { return Word != null; } }
    public Dictionary<Letter, Node> Edges = new Dictionary<Letter, Node>();
  }

  public Node Root = new Node();

  public Trie(string[] words)
  {
    for (int w = 0; w < words.Length; w++)
    {
      var word = words[w];
      var node = Root;
      for (int len = 1; len <= word.Length; len++)
      {
        var letter = word[len - 1];
        Node next;
        if (!node.Edges.TryGetValue(letter, out next))
        {
          next = new Node();
          if (len == word.Length)
          {
            next.Word = word;
          }
          node.Edges.Add(letter, next);
        }
        node = next;
      }
    }
  }