Perl Weekly Challenge 230.
My solutions (task 1 and task 2 ) to the The Weekly Challenge - 230.
Task 1: Separate Digits
Submitted by: Mohammad S Anwar
You are given an array of positive integers.
Write a script to separate the given array into single digits.
Example 1
Input: @ints = (1, 34, 5, 6)
Output: (1, 3, 4, 5, 6)
Example 2
Input: @ints = (1, 24, 51, 60)
Output: (1, 2, 4, 5, 1, 6, 0)
Assuming the input is correct, I just have to split it into
characters.
Example 1:
perl -E 'say join " ", @ARGV, " -> ", map {split ""} @ARGV' 1 34 5 6
Results:
1 34 5 6 -> 1 3 4 5 6
Example 2:
perl -E 'say join " ", @ARGV, " -> ", map {split ""} @ARGV' 1 24 51 60
Results:
1 24 51 50 -> 1 2 4 5 1 5 0
Full code:
1 # Perl weekly challenge 230
2 # Task 1: Separate Digits
3 #
4 # See https://wlmb.github.io/2023/08/14/PWC230/#task-1-separate-digits
5 use v5.36;
6 use List::Util qw(all);
7 die <<~"FIN" unless @ARGV;
8 Usage: $0 N1 [N2..]
9 to separate the positive integers N1 N2... into their decimal digits.
10 FIN
11 for(@ARGV){ # Check input
12 die "Expected only positive integers: $_" unless /^\d+$/;
13 }
14 say join " ", @ARGV, " -> ", map {split ""} @ARGV;
Examples:
./ch-1.pl 1 34 5 6
./ch-1.pl 1 24 51 60
Results:
1 34 5 6 -> 1 3 4 5 6
1 24 51 60 -> 1 2 4 5 1 6 0
Results:
1 34 5 6 -> 1 3 4 5 6 a
1 24 51 60 -> 1 2 4 5 1 6 0
Task 2: Count Words
Submitted by: Mohammad S Anwar
You are given an array of words made up of alphabetic characters and a prefix.
Write a script to return the count of words that starts with the given prefix.
Example 1
Input: @words = ("pay", "attention", "practice", "attend")
$prefix = "at"
Ouput: 2
Two words "attention" and "attend" starts with the given prefix "at".
Example 2
Input: @words = ("janet", "julia", "java", "javascript")
$prefix = "ja"
Ouput: 3
Three words "janet", "java" and "javascripr" starts with the given prefix "ja".
I assume the prefix and the words are given in @ARGV. I further
assume that uppercase is distinct from lowercase. Then, I can use the
prefix to build a regular expression with which I filter the words and
count the number of elements.
Example 1:
perl -E '($p,@w)=@ARGV; say "Prefix: $p, Words: @w, Count: ", 0+grep{/^$p/}@w
' at pay attention practice attend
Results:
Prefix: at, Words: pay attention practice attend, Count: 2
Example 2:
perl -E '($p,@w)=@ARGV; say "Prefix: $p, Words: @w, Count: ", 0+grep{/^$p/}@w
' ja janet julia java javascript
Results:
Prefix: ja, Words: janet julia java javascript, Count: 3
Notice that Perl has some curious behaviour sometimes when converting some collections into scalars, as illustrated below:
perl -E 'say "0+(0,1,2)->", 0+(0,1,2); say "0+(0..2)->", 0+(0..2);
say "0+map{\$_}(0..2)->", 0+map{$_}(0..2);'
Results:
0+(0,1,2)->2
0+(0..2)->1
0+map{$_}(0..2)->3
So it is a good idea to check if your conversion of collections to a scalar does what is expected. Actually, I can’t figure now the second example nor the following:
perl -E 'say "0+1..3->", 0+1..3; say "1+1..3->", 1+1..3;
say "2+1..3->", 2+1..3; say "3+1..3->", 3+1..3;'
Results:
0+1..3->123
1+1..3->23
2+1..3->3
3+1..3->
The full code is:
1 # Perl weekly challenge 230
2 # Task 2: Count Words
3 #
4 # See https://wlmb.github.io/2023/08/14/PWC230/#task-2-count-words
5 use v5.36;
6 die <<~"FIN" unless @ARGV>=2;
7 Usage: $0 prefix W1 [W2...]
8 to count how many of the words W1, W2... start with the prefix.
9 FIN
10 my ($prefix ,@words)=@ARGV;
11 say "Prefix: $prefix, Words: @words, Count: ", 0+grep {/^$prefix/} @words;
Examples:
./ch-2.pl at pay attention practice attend
./ch-2.pl ja janet julia java javascript
Results:
Prefix: at, Words: pay attention practice attend, Count: 2
Prefix: ja, Words: janet julia java javascript, Count: 3
Notice that the program allows a regular expression as prefix, so it could be used as follows:
./ch-2.pl "at|ja" pay attention practice attend janet julia java javascript
Results:
Prefix: at|ja, Words: pay attention practice attend janet julia java javascript, Count: 5