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# Perl Weekly Challenge #131
You can find more information about this weeks, and previous weeks challenges at:
https://theweeklychallenge.org/
If you are not already doing the challenge - it is a good place to practise your
**perl** or **raku**. If it is not **perl** or **raku** you develop in - you can
submit solutions in whichever language you feel comfortable with.
You can find the solutions here on github at:
https://github.com/drbaggy/perlweeklychallenge-club/tree/master/challenge-131/james-smith/perl
# Task 1 - Consecutive Arrays
***You are given a sorted list of unique positive integers. Write a script to return list of arrays where the arrays are consecutive integers.***
## The solution
There isn't much to the solution, we are going to return the data as an array of arrayrefs each containing consecutive numbers.
* We start by creating our first arrayref containing the first value. {for the `if` code to work without an edge case we need in element in our first arrayref to compare against)
* We then loop through the values:
* if the next number is 1 greater than the last value in the last arrayref. We push it there,
* otherwise we create a new arrayref and push it on the end of our array.
* We "cheat" a bit with the `if` statement - by replace `if( $a ) { $b } else { $c }` with `($a) ? ($b) : ($c)` this means we can use it inline within a `foreach` loop.
```perl
sub conseq {
my @val = @{$_[0]};
my @res = ( [shift @val] );
( $_ == 1 + $res[-1][-1] ) ? (push @{$res[-1]},$_) : (push @res,[$_]) for @val;
\@res;
}
```
# Task 2 - Find Pairs
***You are given a string of delimiter pairs and a string to search. Write a script to return two strings, the first with any characters matching the 'opening character' set, the second with any matching the 'closing character' set.***
## Solution
We solve this with a one liner.... which is below:
```perl
sub find_pairs {
map { join '', $_[1] =~ /$_/g }
map { '(['.quotemeta($_).'])' }
map { join '', $_[0] =~ /$_/g }
'(.).?', '.(.?)';
}
```
A bit of an explanation on this one....
* Working backwards we define two regex `(.).` & `.(.)` these when combined with `/g` return alternate characters in the string
either starting from the first char or the 2nd.
* We then join these together to get two lists of characters.
* We convert them into a regex by using quotemeta to remove the "specialness" and then wrapping them in "([ ])" to capture them
* We just run this regex against our original string (with `/g` again) to get results.
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