Mock interview - I was the interviewee

FindWordsInDictionary.cs

/*

Given a 2D board and a list of words from the dictionary, find all words in the board.

Each word must be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same letter cell may not be used more than once in a word.

Input: 
words = ["oath","pea","eat","rain"] and board =
[
  ['o','a','a','n'],
  ['e','t','a','e'],
  ['i','h','k','r'],
  ['i','f','l','v']
]

Output: ["eat","oath"]

letter 
   a b c  .............z
   
   o     p
   /     /
  a      e
  /    /
 t 
 /
 h 

e
/
a
/
t

r
/
a
/
i
/
n

constraint: 

*/

using System;

// To execute C#, please define "static void Main" on a class
// named Solution.

class Solution
{
    static void Main(string[] args)
    {
        for (var i = 0; i < 5; i++)
        {
            Console.WriteLine("Hello, World");
        }
    }
    
    internal class Trie
    {
        public  char     Symbol{get; set;}
        public  Trie[26] Children {get; set;}
        bool    IsWord {get; set;}
        
        public Trie()
        {
            // 
        }
        
        // add
        // search 
        
    }
    
    ///
    public static IList<string> FindWords(char[,] board, string[] words) {
        if(board == null || words == null)
            return new List<string>(); 
        
        var dummyNode = new Trie(); // letter -> 
        putAllWordInTrie(dummyNode, words);
        
        var rows = board.GetLength(0);
        var cols = board.GetLength(1);
        
        var wordsFound = new List<string>(); 
        
        ///
        var visited = new bool[rows,cols]; //visited true/ false, 0, 1, 2
        
        for(int row = 0 ; row < rows; row++)
        {
            for(int col = 0; col < cols; col++)
            {
                var current = visited[row, col];
                if(current)
                    continue; 
                
                searchTrie(dummyNode, row, col, visited, board, wordsFound);
            }
        }
        
        return wordsFound; 
    }
    
    private static searchTrie(Trie dummyNode, int startRow, int startCol, bool[,] visited, char[,] board, IList<string> wordsFound)
    {
        var current = board[startRow, startCol];
        
        //
        var next = dummyNode.Children[current - 'a']; 
        if(next == null)
            return; 
        if(next.IsWord)
        {
            wordsFound.Add(); // words
        }
        
    }
}