Step by Step solution about How to resolve the algorithm Inverted index step by step in the C# programming language

This C# code implements an inverted index that maps words to the files where they appear. It takes a list of files as input and a search term, and then prints out the files where the search term appears.

Here is a detailed explanation of the code:

1. Invert method: This method takes a dictionary as input and returns an inverted index. The inverted index is a dictionary where the keys are the values from the original dictionary, and the values are the keys from the original dictionary. For example, if the original dictionary is { "key1": ["value1", "value2"], "key2": ["value3"] }, the inverted index would be { "value1": ["key1"], "value2": ["key1"], "value3": ["key2"] }.

2. Main method: This is the entry point of the program. It first prompts the user for a list of files and a search term. It then reads the files into memory and creates a dictionary where the keys are the filenames and the values are the words in the files. It then calls the Invert method to create an inverted index, and finally prints out the files where the search term appears.

Here is an example of how to use the program:

files: file1 file2 file3
find: what
what found in: file1 file2

In this example, the program is given three files as input (file1, file2, and file3) and a search term (what). The program then prints out the files where the search term appears (file1 and file2).

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

class InvertedIndex
{
    static Dictionary<TItem, IEnumerable<TKey>> Invert<TKey, TItem>(Dictionary<TKey, IEnumerable<TItem>> dictionary)
    {
        return dictionary
            .SelectMany(keyValuePair => keyValuePair.Value.Select(item => new KeyValuePair<TItem, TKey>(item, keyValuePair.Key)))
            .GroupBy(keyValuePair => keyValuePair.Key)
            .ToDictionary(group => group.Key, group => group.Select(keyValuePair => keyValuePair.Value));
    }

    static void Main()
    {
        Console.Write("files: ");
        var files = Console.ReadLine();
        Console.Write("find: ");
        var find = Console.ReadLine();
        var dictionary = files.Split().ToDictionary(file => file, file => File.ReadAllText(file).Split().AsEnumerable());
        Console.WriteLine("{0} found in: {1}", find, string.Join(" ", Invert(dictionary)[find]));
    }
}


files: file1 file2 file3
find: what
what found in: file1 file2