Solve the NY Times' Letter Boxed game in 2 guesses (modified version of KV's code/algorithm)

boxed.py

from time import time
import re
import sys


def get_words(filename='words.txt'):
    # https://raw.githubusercontent.com/dwyl/english-words/master/words.txt
    with open(filename) as f:
        return [line.strip() for line in f]


def is_valid(word, box, pat):
    if not pat.fullmatch(word):
        return False

    prev_side = None
    for c in word:
        side = box[c]
        if side == prev_side:
            return False
        prev_side = side
    return True


def find_solutions(possibilities):
    lasts = set(s[-1] for s in possibilities)
    # Possibilities Starting With Letter => pswl
    pswl = {l: [s for s in possibilities if s[0] == l] for l in lasts}
    solutions = []
    for s in possibilities:
        for t in pswl[s[-1]]:
            if len(set(s + t)) == 12:
                solutions.append((s, t))
    return solutions


def main(puzzle):
    words = get_words()

    start = time()
    box = {c: i//3 for i, c in enumerate(puzzle)}
    pat = re.compile("^[%s]+" % puzzle)
    possibilities = [w for w in words if is_valid(w, box, pat)]
    solutions = find_solutions(possibilities)

    for s, t in solutions:
        print("Success! %s + %s" % (s, t))

    print("%2.3fs" % (time() - start))


if __name__ == '__main__':
    try:
        main(sys.argv[1])
    except IndexError:
        puzzle = 'IFTELHDRWMAO'.lower()
        main(puzzle)

Oh! this is how the website owner found two word solutions of letter boxed puzzle within few minutes. i wounder how they can quickly give today Letterboxed answers of daily NYT puzzle and publish it on their website within 5 minutes. It took me half an hour to solve the puzzle. I am not much technical and coding person but i got an idea.