Weekly Challenge: Validating Words

Weekly Challenge 353

Each week Mohammad S. Anwar sends out The Weekly Challenge, a chance for all of us to come up with solutions to two weekly tasks. My solutions are written in Python first, and then converted to Perl. It's a great way for us all to practice some coding.

Challenge, My solutions

Task 1: Max Words

Task

You are given an array of sentences.

Write a script to return the maximum number of words that appear in a single sentence.

My solution

There was a error in the original example. Like a good hacker, I raised a pull request to fix it.

This seems pretty straight forward. I strip any leading and trailing white space, and then count the words in the string (separate the sentence by any white space). I have a variable called max_words that has a running total of the maximum word count so far.

def max_words(sentences: list) -> int:
    max_words = 0

    for sentence in sentences:
        word_count = len(sentence.strip().split())
        if word_count > max_words:
            max_words = word_count


    return max_words

The Perl code follows the same logic. It has a Perl-ism that using a scalar for an array (using the split function in this case) will assign the number of elements to the variable.

sub main (@sentences) {
    my $max_words = 0;

    foreach my $sentence (@sentences) {
        $sentence =~ s/^\s+|\s+$//g;

        my $word_count = split( /\s+/, $sentence );
        if ( $word_count > $max_words ) {
            $max_words = $word_count;
        }
    }

    say $max_words;
}

Examples

$ ./ch-1.py "Hello world" "This is a test" "Perl is great"
4

$ ./ch-1.py "Single"
1

$ ./ch-1.py "Short" "This sentence has seven words in total" "A B C" "Just four words here"
7

$ ./ch-1.py "One" "Two parts" "Three part phrase" ""
3

$ ./ch-1.py "The quick brown fox jumps over the lazy dog" "A" "She sells seashells by the seashore" "To be or not to be that is the question"
10

Task 2: Validate Coupon

Task

You are given three arrays, @codes, @names and @status.

Write a script to validate codes in the given array.

A code is valid when the following conditions are true:

• codes[i] is non-empty and consists only of alphanumeric characters (a-z, A-Z, 0-9) and underscores (_).
• names[i] is one of the following four categories: "electronics", "grocery", "pharmacy", "restaurant".
• status[i] is true.

Return an array of booleans indicating validity: output[i] is true if and only if codes[i], names[i] and status[i] are all valid.

My solution

For input from the command line, I take triplets of a code, a name and a status.

For this task, I start with an empty list (array in Perl) called output. I then have a loop - with the variable i - that starts at 0 to one less than the length of the list.

For each iteration I start by setting the is_valid variable to True (the string true in Perl). I check that the specified criteria are met and set the is_valid variable to False if it isn't. Finally I append the is_valid variable to the output list.

def validate_codes(codes: list, names: list, status: list) -> list:
    output = []

    for i in range(len(codes)):
        is_valid = True
        if re.match(r'^[A-Za-z0-9_]+$', codes[i]) is None:
            is_valid = False
        elif names[i] not in ["electronics", "grocery", "pharmacy", "restaurant"]:
            is_valid = False
        elif status[i].lower() == "false":
            # The status is a string of 'true' or 'false', not boolean type.
            is_valid = False
        elif status[i].lower() != 'true':
            raise ValueError(f"Status must be 'true' or 'false', not '{status[i].lower()}'")
        output.append(is_valid)

    return output

The Perl solution follows the same logic.

Examples

$ ./ch-1.py A123 electronics true B_456 restaurant false C789 electronics true D@1 pharmacy true E123 grocery true
1

$ ./ch-2.py A123 electronics true B_456 restaurant false C789 electronics true D@1 pharmacy true E123 grocery true
[True, False, True, False, True]

$ ./ch-2.py Z_9 pharmacy true AB_12 electronics true G01 grocery false X99 electronics true test unknown true
[True, True, False, True, False]

$ ./ch-2.py _123 restaurant true 123 electronics true "" electronics false Coupon_A pharmacy true Alpha grocery true
[True, True, False, True, True]

$ ./ch-2.py ITEM_1 electronics true ITEM_2 electronics true ITEM_3 grocery true ITEM_4 grocery true
[True, True, True, True]

$ ./ch-2.py CAFE_X restaurant true ELEC_100 electronics true FOOD_1 grocery true DRUG_A pharmacy true ELEC_99 electronics false
[True, True, True, True, False]