Development - Advanced, exercise 12

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The function all tokens string generation is the process of creating the set of all the possible strings one can create combining, in a strict alphabetical order, either some of or all the tokens (i.e. strings) in a particular input seed (possibly unordered) list. For instance, considering the list of tokens containing the strings "home", "ball", and "sea", the set of all the possible strings of tokens one can generate includes the strings "ball", "home", "sea", "ball home", "home sea", and "ball home sea". Please note that the string "ball see" is not included in the set to return because, even if the tokens in such string are ordered alphabetically, they are not strictly ordered since there is another token, i.e. "home", which would have followed the token "ball".

Write a function in Python – def all_tokens_string_gen(tokens) – that takes in input the list of tokens (tokens), and that returns the set of all the strings that one can generate using all the tokens as illustrated above.

Solution

# Test case for the function
def test_all_tokens_string_gen(tokens, expected):
    result = all_tokens_string_gen(tokens)
    if expected == result:
        return True
    else:
        return False


# Code of the function
def all_tokens_string_gen(tokens):
    result = set()
    alfa_tokens = sorted(tokens)
    len_tokens = len(tokens)

    for idx in range(len_tokens):
        str_list = []
        for jdx in range(idx, len_tokens):
            str_list.append(alfa_tokens[jdx])
            result.add("".join(str_list))

    return result


# Tests
print(test_all_tokens_string_gen(["a"], {"a"}))
print(test_all_tokens_string_gen(["a", "b"], {"a", "b", "ab"}))
print(test_all_tokens_string_gen(["a", "c", "b"], {"a", "b", "c", "ab", "bc", "abc"}))
print(test_all_tokens_string_gen(["a", "c", "b", "d"], {"a", "b", "c", "d", "ab", "bc", "cd",
                                                        "abc", "bcd", "abcd"}))

Additional material

The runnable Python file is available online.