| 18 July 2025 | Challenge 330 |
Capital Cleared
Task 1: Clear Digits
Submitted by: Mohammad Sajid Anwar
You are given a string containing only lower case English letters and digits.
Write a script to remove all digits by removing the first digit and the closest non-digit character to its left.
Example 1
Input: $str = "cab12"
Output: "c"
Round 1: remove "1" then "b" => "ca2"
Round 2: remove "2" then "a" => "c"
Example 2
Input: $str = "xy99"
Output: ""
Round 1: remove "9" then "y" => "x9"
Round 2: remove "9" then "x" => ""
Example 3
Input: $str = "pa1erl"
Output: "perl"
Solution
Repeatedly remove one digit and its preceeding non-digit.
Any character having the Unicode property “Number”, such as the superscript ¹ (U+00B9) is regarded as a digit, e.g. a¹b shall be transformed to b.
As it is not specified how to handle leading digits, it is assumed these shall be removed.
use strict;
use warnings;
use experimental 'signatures';
sub clear_digits ($str) {
1 while $str =~ s/\P{N}?\p{N}//;
$str;
}
See the full solution to task 1.
Task 2: Title Capital
Submitted by: Mohammad Sajid Anwar
You are given a string made up of one or more words separated by a single space.
Write a script to capitalise the given title. If the word length is 1 or 2 then convert the word to lowercase otherwise make the first character uppercase and remaining lowercase.
Example 1
Input: $str = "PERL IS gREAT"
Output: "Perl is Great"
Example 2
Input: $str = "THE weekly challenge"
Output: "The Weekly Challenge"
Example 3
Input: $str = "YoU ARE A stAR"
Output: "You Are a Star"
Solution
Convert the whole given Unicode string to lower case and title-case all words having at least three characters.
There is a subtle difference between upper case and title case for digraphs.
Consider the (lower case) Bosnian letter lj (U+01C9) that has LJ (U+01C7) as upper case and Lj (U+01C8) as title case.
This implementation will convert the words’ initial letters to title case.
use strict;
use warnings;
sub title_capital {
lc(shift) =~ s/\w{3,}/\u$&/gr;
}
See the full solution to task 2.
If you have a question about this post or if you like to comment on it, feel free to open an issue in my github repository.