{"@attributes":{"version":"2.0"},"channel":{"title":"DEV Community: Simon Green","description":"The latest articles on DEV Community by Simon Green (@simongreennet).","link":"https:\/\/dev.to\/simongreennet","image":{"url":"https:\/\/media2.dev.to\/dynamic\/image\/width=90,height=90,fit=cover,gravity=auto,format=auto\/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F472699%2Feb7bd146-a3b0-41a6-a0b4-22653730bb55.png","title":"DEV Community: Simon Green","link":"https:\/\/dev.to\/simongreennet"},"language":"en","item":[{"title":"Happy 7th birthday TWC!","pubDate":"Mon, 23 Mar 2026 12:34:59 +0000","link":"https:\/\/dev.to\/simongreennet\/happy-7th-birthday-twc-lpk","guid":"https:\/\/dev.to\/simongreennet\/happy-7th-birthday-twc-lpk","description":"

\n \n \n Weekly Challenge 366\n<\/h2>\n\n

It was seven years ago that Mohammad sent out the first challenge<\/a> to Team PWC (as it was then known). Thank you very much for all your work over the seven years.<\/p>\n\n

Each week Mohammad S. Anwar sends out The Weekly Challenge<\/a>, 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. Unless otherwise stated, Copilot (and other AI tools) have NOT been used to generate the solution. It's a great way for us all to practice some coding.<\/p>\n\n

Challenge<\/a>, My solutions<\/a><\/p>\n\n

\n \n \n Task 1: Count Prefixes\n<\/h2>\n\n

\n \n \n Task\n<\/h3>\n\n

You are given an array of words and a string (contains only lowercase English letters).<\/p>\n\n

Write a script to return the number of words in the given array that are a prefix of the given string.<\/p>\n\n

\n \n \n My solution\n<\/h3>\n\n

This is a one-liner in Python. It should be pretty self-explanatory. Given a list called array<\/code> and a string called prefix<\/code>, it counts the number of items in the list where the first letters of the prefix match the word.
\n<\/p>\n\n

\n
def<\/span> count_prefixes<\/span>(<\/span>array<\/span>:<\/span> list<\/span>,<\/span> prefix<\/span>:<\/span> str<\/span>)<\/span> -><\/span> int<\/span>:<\/span>\n    return<\/span> sum<\/span>(<\/span>1<\/span> for<\/span> word<\/span> in<\/span> array<\/span> if<\/span> prefix<\/span>[:<\/span>len<\/span>(<\/span>word<\/span>)]<\/span> ==<\/span> word<\/span>)<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
The Perl solution uses the grep function to perform the counting. In a scalar context, grep returns the number of matching items.
\n<\/p>\n\n
\n
sub <\/span>main<\/span> (@array) {<\/span>\n    my<\/span> $prefix<\/span> =<\/span> pop<\/span>(<\/span>@array<\/span>);<\/span>\n    my<\/span> $count<\/span>  =<\/span> grep<\/span> {<\/span> substr<\/span>(<\/span> $prefix<\/span>,<\/span> 0<\/span>,<\/span> length<\/span>(<\/span>$_<\/span>)<\/span> )<\/span> eq<\/span> $_<\/span> }<\/span> @array<\/span>;<\/span>\n    say<\/span> $count<\/span>;<\/span>\n}<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
\n  \n  \n  Examples\n<\/h3>\n\n\n\n
\n
$ <\/span>.\/ch-1.py a ap app apple banana apple\n4\n\n$ <\/span>.\/ch-1.py cat <\/span>dog fish bird\n0\n\n$ <\/span>.\/ch-1.py hello he hello heaven he hello\n4\n\n$ <\/span>.\/ch-1.py \"\"<\/span> code coding cod coding\n3\n\n$ <\/span>.\/ch-1.py p pr <\/span>pro prog progr progra program program\n7\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
\n  \n  \n  Task 2: Valid Times\n<\/h2>\n\n
\n  \n  \n  Task\n<\/h3>\n\n
You are given a time in the form HH:MM<\/code>. The earliest possible time is 00:00<\/code> and the latest possible time is 23:59<\/code>. In the string time, the digits represented by the ?<\/code> symbol are unknown, and must be replaced with a digit from 0 to 9.<\/p>\n\n
Write a script to return the count different ways we can make it a valid time.<\/p>\n\n
\n  \n  \n  My solution\n<\/h3>\n\n
This is an interesting challenge as the solution is not straight forward. There are a few approaches that can be taken. One option is to calculate all 1440 minutes in a day and see if it matched the expected pattern.<\/p>\n\n
The approach I took was to calculate the possible hours and possible minutes, and multiplying both figures to return a result.<\/p>\n\n
I start by using a regular expression to check if the time is valid. As the question mark ?<\/code> is within square brackets [ ]<\/code> this is taken as a literal character.
\n<\/p>\n\n
\n
def<\/span> valid_times<\/span>(<\/span>input_string<\/span>:<\/span> str<\/span>)<\/span> -><\/span> int<\/span>:<\/span>\n    if<\/span> not<\/span> re<\/span>.<\/span>search<\/span>(<\/span>r<\/span>'<\/span>^([0-1?][0-9?]|2[0-3?]):[0-5?][0-9?]$<\/span>'<\/span>,<\/span> input_string<\/span>):<\/span>\n        raise<\/span> ValueError<\/span>(<\/span>\"<\/span>Input is not in the expected format (HH:MM)<\/span>\"<\/span>)<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
The next task is calculating the number of valid hours.<\/p>\n\n
    \n
  1. If the hours is ??<\/code>, then there are 24 valid hours.<\/li>\n
  2. If the first character is a question there are 3 valid hours if the second digit is less than four (e.g. 02 12 22), or 2 if it is 4 or greater (e.g. 04 14).<\/li>\n
  3. If the second character is a question mark, there are 4 valid hours if the first digit is 2, or 10 valid hours otherwise.<\/li>\n
  4. If hours have no questions marks, there is only one valid hour.\n<\/li>\n<\/ol>\n\n
    \n
        # Compute the hours\n<\/span>    if<\/span> input_string<\/span>[:<\/span>2<\/span>]<\/span> ==<\/span> \"<\/span>??<\/span>\"<\/span>:<\/span>\n        hours<\/span> =<\/span> 24<\/span>\n    elif<\/span> input_string<\/span>[:<\/span>1<\/span>]<\/span> ==<\/span> \"<\/span>?<\/span>\"<\/span>:<\/span>\n        hours<\/span> =<\/span> 3<\/span> if<\/span> int<\/span>(<\/span>input_string<\/span>[<\/span>1<\/span>:<\/span>2<\/span>])<\/span> <<\/span> 4<\/span> else<\/span> 2<\/span>\n    elif<\/span> input_string<\/span>[<\/span>1<\/span>:<\/span>2<\/span>]<\/span> ==<\/span> \"<\/span>?<\/span>\"<\/span>:<\/span>\n        hours<\/span> =<\/span> 4<\/span> if<\/span> input_string<\/span>[:<\/span>1<\/span>]<\/span> ==<\/span> \"<\/span>2<\/span>\"<\/span> else<\/span> 10<\/span>\n    else<\/span>:<\/span>\n        hours<\/span> =<\/span> 1<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
    Thankfully calculating the number of valid minutes is a little easier.<\/p>\n\n
      \n
    1. If the minutes is ??<\/code>, then there are sixty valid minutes.<\/li>\n
    2. If the first character is a question mark, then there are six valid minutes (e.g. 06 16 26 36 46 56).<\/li>\n
    3. If the second characters is a question mark, there are ten valid minutes (e.g. 50 51 ... 58 59).<\/li>\n
    4. If the minutes have no question marks, there is only one valid minute.\n<\/li>\n<\/ol>\n\n
      \n
          if<\/span> input_string<\/span>[<\/span>3<\/span>:]<\/span> ==<\/span> \"<\/span>??<\/span>\"<\/span>:<\/span>\n        minutes<\/span> =<\/span> 60<\/span>\n    elif<\/span> input_string<\/span>[<\/span>3<\/span>:<\/span>4<\/span>]<\/span> ==<\/span> \"<\/span>?<\/span>\"<\/span>:<\/span>\n        minutes<\/span> =<\/span> 6<\/span>\n    elif<\/span> input_string<\/span>[<\/span>4<\/span>:]<\/span> ==<\/span> \"<\/span>?<\/span>\"<\/span>:<\/span>\n        minutes<\/span> =<\/span> 10<\/span>\n    else<\/span>:<\/span>\n        minutes<\/span> =<\/span> 1<\/span>\n\n    return<\/span> hours<\/span> *<\/span> minutes<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
      The Perl solution follows the same logic as the Python solution.<\/p>\n\n
      \n  \n  \n  Examples\n<\/h3>\n\n\n\n
      \n
      $ <\/span>.\/ch-2.py ?2:34\n3\n\n$ <\/span>.\/ch-2.py ?4:?0\n12\n\n$ <\/span>.\/ch-2.py ??:??\n1440\n\n$ <\/span>.\/ch-2.py ?3:45\n3\n\n$ <\/span>.\/ch-2.py 2?:15\n4\n<\/code><\/pre>\n\n<\/div>\n\n\n\n","category":["python","perl","theweeklychallenge"]},{"title":"Weekly Challenge: Counting the index","pubDate":"Thu, 19 Mar 2026 07:30:11 +0000","link":"https:\/\/dev.to\/simongreennet\/weekly-challenge-counting-the-index-oe1","guid":"https:\/\/dev.to\/simongreennet\/weekly-challenge-counting-the-index-oe1","description":"
      \n  \n  \n  Weekly Challenge 365\n<\/h2>\n\n
      Each week Mohammad S. Anwar sends out The Weekly Challenge<\/a>, 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. Unless otherwise stated, Copilot (and other AI tools) have NOT been used to generate the solution. It's a great way for us all to practice some coding.<\/p>\n\n
      Challenge<\/a>, My solutions<\/a><\/p>\n\n
      \n  \n  \n  Task 1: Alphabet Index Digit Sum\n<\/h2>\n\n
      \n  \n  \n  Task\n<\/h3>\n\n
      You are given a string $str<\/code> consisting of lowercase English letters, and an integer $k<\/code>.<\/p>\n\n
      Write a script to convert a lowercase string into numbers using alphabet positions (a=1 \u2026 z=26), concatenate them to form an integer, then compute the sum of its digits repeatedly $k<\/code> times, returning the final value.<\/p>\n\n
      \n  \n  \n  My solution\n<\/h3>\n\n
      This is a task of two parts. The first is to take the letters from input_string<\/code> (as str<\/code> is a reserved word in Python) to create a number. For this I use string.ascii_lowercase.index(letter)+1<\/code> to get each letter and append it to the digits<\/code> variable. The +1<\/code> is because the letters start at 1<\/code>, not 0<\/code>.
      \n<\/p>\n\n
      \n
      def<\/span> aid_sum<\/span>(<\/span>input_string<\/span>:<\/span> str<\/span>,<\/span> k<\/span>:<\/span> int<\/span>)<\/span> -><\/span> int<\/span>:<\/span>\n    digits<\/span> =<\/span> ''<\/span>\n    for<\/span> letter<\/span> in<\/span> input_string<\/span>:<\/span>\n        try<\/span>:<\/span>\n            digits<\/span> +=<\/span> str<\/span>(<\/span>string<\/span>.<\/span>ascii_lowercase<\/span>.<\/span>index<\/span>(<\/span>letter<\/span>)<\/span>+<\/span>1<\/span>)<\/span>\n        except<\/span> ValueError<\/span>:<\/span>\n            raise<\/span> ValueError<\/span>(<\/span>\n                f<\/span>\"<\/span>The character <\/span>'<\/span>{<\/span>letter<\/span>}<\/span>'<\/span> does not appear to be a lower case letter<\/span>\"<\/span>\n            )<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
      The second part is to compute the sums of all the digits a specified number of times. For this I have a loop that performs this. It's a little clunky as Python treats strings and integers differently. If I have a single digit, I exit the loop early as further repetitions won't change the result.
      \n<\/p>\n\n
      \n
          for<\/span> _<\/span> in<\/span> range<\/span>(<\/span>k<\/span>):<\/span>\n        digits<\/span> =<\/span> str<\/span>(<\/span>sum<\/span>(<\/span>int<\/span>(<\/span>i<\/span>)<\/span> for<\/span> i<\/span> in<\/span> digits<\/span>))<\/span>\n        if<\/span> len<\/span>(<\/span>digits<\/span>)<\/span> ==<\/span> 1<\/span>:<\/span>\n            break<\/span>\n\n    return<\/span> int<\/span>(<\/span>digits<\/span>)<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
      As Perl doesn't care about strings vs integers (with a few exceptions), the code is more straight forward. The index<\/a> function is used to find the position of the letter in the alphabet.
      \n<\/p>\n\n
      \n
      sub <\/span>main<\/span> ( $input_string, $k ) {<\/span>\n    my<\/span> $alphabet<\/span> =<\/span> join<\/span>(<\/span> \"\",<\/span> \"<\/span>a<\/span>\"<\/span> ..<\/span> \"<\/span>z<\/span>\"<\/span> );<\/span>\n    my<\/span> $digits<\/span>   =<\/span> '';<\/span>\n\n    foreach<\/span> my<\/span> $letter<\/span> (<\/span> split<\/span> \/\/<\/span>,<\/span> $input_string<\/span> )<\/span> {<\/span>\n        my<\/span> $idx<\/span> =<\/span> index<\/span>(<\/span> $alphabet<\/span>,<\/span> $letter<\/span> );<\/span>\n        if<\/span> (<\/span> $idx<\/span> ==<\/span> -<\/span>1<\/span> )<\/span> {<\/span>\n            die<\/span>\n              \"<\/span>The character '<\/span>$letter<\/span>' does not appear to be a lower case letter<\/span>\\n<\/span>\";<\/span>\n        }<\/span>\n\n        $digits<\/span> .=<\/span> $idx<\/span> +<\/span> 1<\/span>;<\/span>\n    }<\/span>\n\n    foreach<\/span> (<\/span> 1<\/span> ..<\/span> $k<\/span> )<\/span> {<\/span>\n        $digits<\/span> =<\/span> sum<\/span>(<\/span> split<\/span> \/\/<\/span>,<\/span> $digits<\/span> );<\/span>\n    }<\/span>\n\n    say<\/span> $digits<\/span>;<\/span>\n}<\/span>\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
      \n  \n  \n  Examples\n<\/h3>\n\n\n\n
      \n
      $ <\/span>.\/ch-1.py abc 1\n6\n\n$ <\/span>.\/ch-1.py az 2\n9\n\n$ <\/span>.\/ch-1.py cat <\/span>1\n6\n\n$ <\/span>.\/ch-1.py dog 2\n8\n\n$ <\/span>.\/ch-1.py perl 3\n6\n<\/code><\/pre>\n\n<\/div>\n\n\n\n
      \n  \n  \n  Task 2: Valid Token Counter\n<\/h2>\n\n
      \n  \n  \n  Task\n<\/h3>\n\n
      You are given a sentence.<\/p>\n\n
      Write a script to split the given sentence into space-separated tokens and count how many are valid words. A token is valid if it contains no digits, has at most one hyphen surrounded by lowercase letters, and at most one punctuation mark (!<\/code>, .<\/code>, ,<\/code>) appearing only at the end.<\/p>\n\n
      \n  \n  \n  My solution\n<\/h3>\n\n
      This is a challenge where regular expression can be used to solve the problem. In both the Python and Perl solution, the regular expression used is ^[a-z]+(\\-[a-z]+)?[!,\\.]?$<\/code>.<\/p>\n\n
      Breaking each part down:<\/p>\n\n