gtwomd

    import numpy as np
    with open("words.txt") as f:
        words = f.read().splitlines()
        f.seek(0)
        chars = np.array(list(ord(c) for c in f.read() if c != '\n')).reshape((-1, 4))

    word_to_index = dict(zip(words, range(len(words))))

    char_flip = np.sum(chars[:, None, :] != chars[None, :, :], axis=2) == 1
    chars_sorted = np.sort(chars, axis=1)
    char_shuffle = np.all(chars_sorted[:, None, :] == chars_sorted[None, :, :], axis=2)

    adj = char_flip | char_shuffle
    np.fill_diagonal(adj, False)
    # import itertools

    def path_recursive(current, end, adj, path, depth):
        if depth <= 0:
            return []
        if current == end:
            return [[*path, end]]
        
        # all_paths = []
        for neighbor in adj[current]:
            if neighbor in path:
                continue
            _path = path_recursive(neighbor, end, adj, [*path, current], depth - 1)
            # all_paths.append(_path)
            if _path:
                return _path

        
        # return list(itertools.chain(*all_paths))
        return []

    def binary_shortest_dist(start, end, adj):
        depth = 1
        adj_n = np.eye(adj.shape[0])
        while depth < 20:
            depth += 1
            adj_n = adj_n @ adj
            if adj_n[start, end]:
                return depth


    def path(start, end, adj):
        start = word_to_index[start.upper()]
        end = word_to_index[end.upper()]
        depth = binary_shortest_dist(start, end, adj)

        print(depth)

        adj = [[i for i in np.nonzero(_adj)[0]] for _adj in adj]

        paths = path_recursive(start, end, adj, [], depth)
        return [[words[i] for i in path] for path in paths]

    path("disc", "zero", adj)