The weekly challenge 332 - Task 2: Odd Letters

 1 #!/usr/bin/env perl
 2 # https://theweeklychallenge.org/blog/perl-weekly-challenge-332/#TASK2
 3 #
 4 # Task 2: Odd Letters
 5 # ===================
 6 #
 7 # You are given a string.
 8 #
 9 # Write a script to find out if each letter in the given string appeared odd number of times.
10 #
11 ## Example 1
12 ##
13 ## Input: $str = "weekly"
14 ## Output: false
15 ##
16 ## w: 1 time
17 ## e: 2 times
18 ## k: 1 time
19 ## l: 1 time
20 ## y: 1 time
21 ##
22 ## The letter 'e' appeared 2 times i.e. even.
23 #
24 #
25 ## Example 2
26 ##
27 ## Input: $str = "perl"
28 ## Output: true
29 #
30 #
31 ## Example 3
32 ##
33 ## Input: $source = "challenge"
34 ## Output: false
35 #
36 ############################################################
37 ##
38 ## discussion
39 ##
40 ############################################################
41 #
42 # We split the input into its individual characters and count
43 # each occurence by using a hash table. In the end, we check
44 # each letter whether it occurs an odd or even number of times.
45 # If any number occurs an even amount of times, we return false
46 # immediately. In the end, we can return true.
47 
48 use v5.36;
49 
50 odd_letters("weekly");
51 odd_letters("perl");
52 odd_letters("challenge");
53 
54 sub odd_letters($str) {
55     say "Input: \"$str\"";
56     my $map = {};
57     foreach my $l (split //, $str) {
58         $map->{$l}++;
59     }
60     foreach my $l (keys %$map) {
61         if( $map->{$l} % 2 == 0) {
62             return say "Output: false";
63         }
64     }
65     say "Output: true";
66 }