The weekly challenge 330 - Task 1: Clear Digits

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-330/#TASK1
 3 #
 4 # Task 1: Clear Digits
 5 # ====================
 6 #
 7 # You are given a string containing only lower case English letters and digits.
 8 #
 9 # Write a script to remove all digits by removing the first digit and the
10 # closest non-digit character to its left.
11 #
12 ## Example 1
13 ##
14 ## Input: $str = "cab12"
15 ## Output: "c"
16 ##
17 ## Round 1: remove "1" then "b" => "ca2"
18 ## Round 2: remove "2" then "a" => "c"
19 #
20 #
21 ## Example 2
22 ##
23 ## Input: $str = "xy99"
24 ## Output: ""
25 ##
26 ## Round 1: remove "9" then "y" => "x9"
27 ## Round 2: remove "9" then "x" => ""
28 #
29 #
30 ## Example 3
31 ##
32 ## Input: $str = "pa1erl"
33 ## Output: "perl"
34 #
35 ############################################################
36 ##
37 ## discussion
38 ##
39 ############################################################
40 #
41 # Long description short, as long as there is still a non-digit
42 # before a digit, remove those two characters.
43 # Note: If the string starts with a digit, but then has other characters before
44 # other digits, this will still remove the later digit. It's not 100% clear
45 # whether this is an allowed input though.
46 
47 use v5.36;
48 
49 clear_digits("cab12");
50 clear_digits("xy99");
51 clear_digits("pa1erl");
52 
53 sub clear_digits($str) {
54     say "Input: \"$str\"";
55     while($str =~ s/[^\d]\d//) {
56     }
57     say "Output: \"$str\"";
58 }