using System;

using System.Collections.Generic;

​

/**

Time complexity O(nm), n is the number of words in dict, m is the average length of words in dict, space complexity O(nm)

**/

public class MagicDictionary 

{

    private Dictionary<int, List<string>> map;

    public MagicDictionary() 

    {

        map = new Dictionary<int, List<string>>();

    }

    public void BuildDict(string[] dictionary) 

    {

        foreach(var str in dictionary)

        {

            if(!map.ContainsKey(str.Length))

                map.Add(str.Length, new List<string>(){ str });

            else

                map[str.Length].Add(str);

        }

    }

    public bool Search(string searchWord) 

    {

        if(!map.ContainsKey(searchWord.Length))

            return false;

        else

        {

            var listOfStrings = map[searchWord.Length];

            foreach(string str in listOfStrings)

            {

                int count = 0;

                for(int i = 0; i < str.Length; i++)

                {

                    if(str[i] != searchWord[i])

                        count++;

                    if(count == 2)

                        break;

                }

                if(count == 1)

                    return true;

            }

            return false;

        }

    }

}

​

public class Program

{

    public static void Main()

    {

        MagicDictionary magicDictionary = new MagicDictionary();

        magicDictionary.BuildDict(new string[]{"hello", "leetcode"});

        var canChangeOneChar = magicDictionary.Search("leetcoded"); // return False

        Console.WriteLine(canChangeOneChar);

    }

}