Step by Step solution about How to resolve the algorithm Word wheel step by step in the JavaScript programming language

The provided JavaScript code defines a function called gridWords that takes a list of strings representing a grid of letters and a list of strings representing lexemes (words) and returns a list of lexemes that can be formed from the letters in the grid.

Here's a breakdown of the code:

1. gridWords function:

   • Takes two arguments:
     • grid: A list of strings representing the rows of a grid of letters.
     • lexemes: A list of strings representing lexemes (words).
   • Returns a new list of strings containing the lexemes that can be formed from the letters in the grid.

2. Inside the gridWords function:

   • wheel: A new string is created by joining all the strings in the grid list and then sorting the resulting string in ascending order. This string represents the letters in the grid arranged in a circular fashion.
   • wSet: A new Set is created from the wheel string. A Set is a collection of unique elements in JavaScript.
   • mid: The middle character of the wheel string is stored in the mid variable.

3. The function then filters the lexemes list using the filter() method. The filter checks each lexeme using a callback function to determine if it should be included in the returned list.

4. The callback function used in the filter:

   • Takes a single argument: w.
   • Converts w to lowercase and sorts its characters.
   • Checks if w has at least three characters and if all of its characters are present in the wSet.
   • Checks if w contains the mid character.
   • Calls the wheelFit function to verify that w can be formed using the letters in the wheel. If wheelFit returns true, it means w can be formed using the grid letters, and it is included in the returned list.

5. wheelFit function:

   • Takes two arguments:
     • wheel: The sorted string representing the grid letters in a circular fashion.
     • word: The sorted string representing the lexeme being checked.
   • The function uses recursion to check if word can be formed using the letters in the wheel. It starts by comparing the first character of wheel with the first character of word. If they match, it moves on to compare the second characters, and so on. If it reaches the end of word without finding any mismatches, it returns true, indicating that word can be formed using the grid letters. Otherwise, it returns false.

6. main function:

   • Defines the entry point of the script.
   • Calls the gridWords function with a grid of letters and a list of lexemes read from a file.
   • The result is a list of lexemes that can be formed from the grid letters, which is then joined into a newline-separated string and returned.

7. Other utility functions:

   • lines: Splits a string into an array of strings based on newline characters.
   • readFile: Reads the contents of a file and returns a string.
   • sort: Sorts an array of elements in ascending order.
   • toLower: Converts a string to lowercase.

When you execute the script, it reads a list of words from a file (typically a dictionary), applies the gridWords function to filter the words based on the grid of letters, and prints the resulting list of words that can be formed using the grid letters.

(() => {
    "use strict";

    // ------------------- WORD WHEEL --------------------

    // gridWords :: [String] -> [String] -> [String]
    const gridWords = grid =>
        lexemes => {
            const
                wheel = sort(toLower(grid.join(""))),
                wSet = new Set(wheel),
                mid = wheel[4];

            return lexemes.filter(w => {
                const cs = [...w];

                return 2 < cs.length && cs.every(
                    c => wSet.has(c)
                ) && cs.some(x => mid === x) && (
                    wheelFit(wheel, cs)
                );
            });
        };


    // wheelFit :: [Char] -> [Char] -> Bool
    const wheelFit = (wheel, word) => {
        const go = (ws, cs) =>
            0 === cs.length ? (
                true
            ) : 0 === ws.length ? (
                false
            ) : ws[0] === cs[0] ? (
                go(ws.slice(1), cs.slice(1))
            ) : go(ws.slice(1), cs);

        return go(wheel, sort(word));
    };


    // ---------------------- TEST -----------------------
    // main :: IO ()
    const main = () =>
        gridWords(["NDE", "OKG", "ELW"])(
            lines(readFile("unixdict.txt"))
        )
        .join("\n");


    // ---------------- GENERIC FUNCTIONS ----------------

    // lines :: String -> [String]
    const lines = s =>
        // A list of strings derived from a single string
        // which is delimited by \n or by \r\n or \r.
        Boolean(s.length) ? (
            s.split(/\r\n|\n|\r/u)
        ) : [];


    // readFile :: FilePath -> IO String
    const readFile = fp => {
        // The contents of a text file at the
        // given file path.
        const
            e = $(),
            ns = $.NSString
            .stringWithContentsOfFileEncodingError(
                $(fp).stringByStandardizingPath,
                $.NSUTF8StringEncoding,
                e
            );

        return ObjC.unwrap(
            ns.isNil() ? (
                e.localizedDescription
            ) : ns
        );
    };


    // sort :: Ord a => [a] -> [a]
    const sort = xs =>
        Array.from(xs).sort();


    // toLower :: String -> String
    const toLower = s =>
        // Lower-case version of string.
        s.toLocaleLowerCase();


    // MAIN ---
    return main();
})();