using System;

using System.Collections.Generic;

using Newtonsoft.Json;

​

public class Card

{

    public string title;

    public string description;

}

​

public class InvertedIndex

{

    public string[] StopWords = {"the", "a", "is"};

    public Dictionary<string, HashSet<Card>> index = new Dictionary<string, HashSet<Card>>();

    public List<Card> lookup(string term)

    {

        index.add

        HashSet<Card> lookupValue;

        if (index.TryGetValue(term, out lookupValue))

        {

            return new List<Card>(lookupValue);

        }

        return new List<Card>();

    }

    public void addToIndex(Card card)

    {

        List<string> tokens = new List<string>();

        tokens.AddRange(tokenize(card.title));

        tokens.AddRange(tokenize(card.description));

        foreach(string token in tokens)

        {

            if(index.ContainsKey(token))

            {

                index[token].Add(card);

            }

            else

            {

                HashSet<Card> newSet = new HashSet<Card>();

                newSet.Add(card);

                index.Add(token, newSet);

            }

        }

    }

    private List<string> tokenize(string str)

    {

        return new List<string>(str.Split(' '));

    }

}

public class Program

{

​

    public static void Main()

    {

        string data = @"[

        {""title"": ""test"",

         ""description"": ""this is a description both""

        },

        {""title"": ""asdasd"",

        ""description"": ""inverted index me both zaddy""

        }

        ]";

        InvertedIndex index = new InvertedIndex();

        List<Card> cards = JsonConvert.DeserializeObject<List<Card>>(data);

​

        foreach (Card card in cards) {

            index.addToIndex(card);

        }

        List<Card> cardsContainingBoth = index.lookup("both");

        foreach(Card match in cardsContainingBoth)

        {

            Console.WriteLine($@"Match: {match.title}/{match.description}");

        }

    }

}