The weekly challenge 378 - Task 1: Second Largest Digit

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-378/#TASK1
 3 #
 4 # Task 1: Second Largest Digit
 5 # ============================
 6 #
 7 # You are given an alphanumeric string.
 8 #
 9 # Write a script to find the second largest distinct digit in the given string.
10 # Return -1 if none found.
11 #
12 ## Example 1
13 ##
14 ## Input: $str = "aaaaa77777"
15 ## Output: -1
16 ##
17 ## The only digit in the given string is 7 and there is no second digit.
18 #
19 ## Example 2
20 ##
21 ## Input: $str = "abcde"
22 ## Output: -1
23 ##
24 ## No numerical digits in the given string.
25 #
26 ## Example 3
27 ##
28 ## Input: $str = "9zero8eight7seven9"
29 ## Output: 8
30 #
31 ## Example 4
32 ##
33 ## Input: $str = "xyz9876543210"
34 ## Output: 8
35 #
36 ## Example 5
37 ##
38 ## Input: $str = "4abc4def2ghi8jkl2"
39 ## Output: 4
40 #
41 ############################################################
42 ##
43 ## discussion
44 ##
45 ############################################################
46 #
47 # We collect all found digits in a hash, then use that to create
48 # a sorted array from those found digits to fill then into an array.
49 # Then we pick the second element from that array, but only if there
50 # are enough. Otherwise, we fail with a return of "-1".
51 
52 use v5.36;
53 
54 second_largest_digit("aaaaa77777");
55 second_largest_digit("abcde");
56 second_largest_digit("9zero8eight7seven9");
57 second_largest_digit("xyz9876543210");
58 second_largest_digit("4abc4def2ghi8jkl2");
59 
60 sub second_largest_digit($str) {
61     say "Input: \"$str\"";
62     my $digits = {};
63     foreach my $c (split //, $str) {
64         next unless $c =~ m/\d/;
65         $digits->{$c} = 1;
66     }
67     my @found_digits = sort { $b <=> $a } keys %$digits;
68     if ( scalar(@found_digits) < 2 ) {
69         say "Output: -1";
70     } else {
71         say "Output: $found_digits[1]";
72     }
73 }