The weekly challenge 318 - Task 1: Group Position

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-318/#TASK1
 3 #
 4 # Task 1: Group Position
 5 # ======================
 6 #
 7 # You are given a string of lowercase letters.
 8 #
 9 # Write a script to find the position of all groups in the given string. Three
10 # or more consecutive letters form a group. Return "” if none found.
11 #
12 ## Example 1
13 ##
14 ## Input: $str = "abccccd"
15 ## Output: "cccc"
16 #
17 #
18 ## Example 2
19 ##
20 ## Input: $str = "aaabcddddeefff"
21 ## Output: "aaa", "dddd", "fff"
22 #
23 #
24 ## Example 3
25 ##
26 ## Input: $str = "abcdd"
27 ## Output: ""
28 #
29 ############################################################
30 ##
31 ## discussion
32 ##
33 ############################################################
34 #
35 # We need to remember the last character and any already existing
36 # substring of $str that consists of only the same character.
37 # If the current character matches the last one, we just add it to
38 # the temporary string. If it doesn't match, we reset $lastchar and
39 # the temporary string to the current character. In the end, we also
40 # capture the current $tmpstr and add it to the result list in case it's
41 # longer than or equal to 3 characters.
42 
43 use v5.36;
44 
45 group_position("abccccd");
46 group_position("aaabcddddeefff");
47 group_position("abcdd");
48 
49 sub group_position($str) {
50     say "Input: \"$str\"";
51     my @result = ();
52 
53     my $tmpstr = "";
54     my $lastchar = "";
55     my @chars = split//, $str;
56     foreach my $char (@chars) {
57         if($char eq $lastchar) {
58             $tmpstr .= $char;
59         } else {
60             if(length($tmpstr) > 2) {
61                 push @result, $tmpstr;
62             }
63             $tmpstr = $char;
64             $lastchar = $char;
65         }
66     }
67     if(length($tmpstr) > 2) {
68         push @result, $tmpstr;
69     }
70 
71     say "Output: \"" . join("\", \"", @result) . "\"";
72 }