Trie

using System;
using System.IO;
using System.Text;

class Node{
    const int ALL_CHAR = 26;
    const int MAX_CHAR = 128;

    private static char []map_char_to_int = new char[MAX_CHAR];
    private static char []map_int_to_char = new char[ALL_CHAR];
    private Node[] Character = new Node[ALL_CHAR];
    private int Count = 0;

    public void init(){
        for(char i = 'a'; i <= 'z'; ++i){
            map_char_to_int[i] = (char)(i - 'a');
            map_int_to_char[i - 'a'] = i;
        }
    }

    private int _find(ref string str, int index){
        if(index == str.Length) return ++this.Count;
        if(Character[map_char_to_int[Convert.ToChar(str[index])]] == null)
            Character[map_char_to_int[Convert.ToChar(str[index])]] = new Node();

        return Character[map_char_to_int[Convert.ToChar(str[index])]]._find(ref str, index + 1);
    }

    public int Find(string str){
        str = str.ToLower();
        return _find(ref str, 0);
    }

    private static StringBuilder current = new StringBuilder();

    public void DFS(){
        if(Count > 0) Console.WriteLine("[{0}={1}] ", current, Count);
        for(int i = 0; i < ALL_CHAR; i++){
            if(Character[i] != null){
                current.Append(map_int_to_char[i]);
                Character[i].DFS();
                current.Remove(current.Length - 1, 1);
            }
        }
    }
}

class word{
    public static void Main(){
        Node trie = new Node();
        trie.init();
        try{
            StreamReader inf = File.OpenText("sampletext.txt");
            string line = inf.ReadLine();
            while(line != null){
                string []sline = line.Split(' ');
                for(int i = 0; i < sline.Length; i++)
                    trie.Find(sline[i]);
                line = inf.ReadLine();
            }
        }catch (Exception e){}
        trie.DFS();
    }
}