The weekly challenge 364 - Task 1: Decrypt String

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-364/#TASK1
 3 #
 4 # Task 1: Decrypt String
 5 # ======================
 6 #
 7 # You are given a string formed by digits and ‘#'.
 8 #
 9 # Write a script to map the given string to English lowercase characters
10 # following the given rules.
11 #
12 ## - Characters 'a' to 'i' are represented by '1' to '9' respectively.
13 ## - Characters 'j' to 'z' are represented by '10#' to '26#' respectively.
14 #
15 ## Example 1
16 ##
17 ## Input: $str = "10#11#12"
18 ## Output: "jkab"
19 ##
20 ## 10# -> j
21 ## 11# -> k
22 ## 1   -> a
23 ## 2   -> b
24 #
25 ## Example 2
26 ##
27 ## Input: $str = "1326#"
28 ## Output: "acz"
29 ##
30 ## 1   -> a
31 ## 3   -> c
32 ## 26# -> z
33 #
34 ## Example 3
35 ##
36 ## Input: $str = "25#24#123"
37 ## Output: "yxabc"
38 ##
39 ## 25# -> y
40 ## 24# -> x
41 ## 1   -> a
42 ## 2   -> b
43 ## 3   -> c
44 #
45 ## Example 4
46 ##
47 ## Input: $str = "20#5"
48 ## Output: "te"
49 ##
50 ## 20# -> t
51 ## 5   -> e
52 #
53 ## Example 5
54 ##
55 ## Input: $str = "1910#26#"
56 ## Output: "aijz"
57 ##
58 ## 1   -> a
59 ## 9   -> i
60 ## 10# -> j
61 ## 26# -> z
62 #
63 ############################################################
64 ##
65 ## discussion
66 ##
67 ############################################################
68 #
69 # As long as we have two digits in front of a "#" at the beginning
70 # of $str, we pick those two digits, add 96 and call chr() on the
71 # result (because "a" is ASCII 97 and we start counting at 1). If
72 # $str doesn't start in two digits and "#", then we pick the first
73 # digits, add 96 and hand the result to chr(). We do that until
74 # there is nothing left in $str.
75 
76 use v5.36;
77 
78 decrypt_string("10#11#12");
79 decrypt_string("1326#");
80 decrypt_string("25#24#123");
81 decrypt_string("20#5");
82 decrypt_string("1910#26#");
83 
84 sub decrypt_string($str) {
85     say "Input: \"$str\"";
86     my $result = "";
87     while(length($str)) {
88         if($str =~ m/(^\d\d)#/) {
89             $result .= chr(96+$1);
90             $str =~ s/...//;
91         } else {
92             $result .= chr(96+ substr($str,0,1,""));
93         }
94     }
95     say "Output: \"$result\"";
96 }