# RabbitFarm

### 2021-11-21

#### Jort Sort the First Five Long Primes

The examples used here are from The Weekly Challenge problem statement and demonstrate the working solution.

## Part 1

You are given a list of numbers. Write a script to implement JortSort. It should return true/false depending if the given list of numbers are already sorted.

### Solution

``````
use strict;
use warnings;
use boolean;

sub jort_sort{
for(my \$i=0; \$i < @_ - 1; \$i++){
return false if \$_[\$i + 1] < \$_[\$i];
}
return true;
}

MAIN:{
print jort_sort(1, 2, 3, 4, 5) . "\n";
print jort_sort(1, 3, 2, 4, 5) . "\n";
}
``````

### Sample Run

``````
\$ perl perl/ch-1.pl
1
0
``````

### Notes

Apparently Jort Sort is a joke sort started by somebody in the JavaScript community. I didn't find it all that funny, but the code to implement it only took a quick minute.

## Part 2

Write a script to generate the first 5 Long Primes.

### Solution

``````
use strict;
use warnings;
use boolean;
use LWP::UserAgent;
use constant PRIME_URL => "http://primes.utm.edu/lists/small/100000.txt";

sub get_primes{
my @primes;
my \$ua = new LWP::UserAgent(
ssl_opts => {verify_hostname => 0}
);
my \$response = \$ua->get(PRIME_URL);
my @lines = split(/\n/,\$response->decoded_content);
foreach my \$line (@lines){
my @p = split(/\s+/, \$line);
unless(@p < 10){
push @primes, @p[1..(@p - 1)];
}
}
return @primes;
}

sub divide{
my(\$n, \$d) = @_;
my @remainders;
my \$q = (int(\$n / \$d)) . ".";
my \$r = \$n % \$d;
push @remainders, \$r;
my @a;
for (0 .. \$d){
\$q .= int(\$r*10 / \$d);
\$r = \$r*10 % \$d;
@a = grep { \$remainders[\$_] == \$r } (0 .. @remainders - 1);
last if(@a);
push @remainders, \$r;
}
my \$r_i = \$a;
my \$i = index(\$q, ".");
my \$decimal_part = substr(\$q, \$i+1);
return substr(\$q, 0, \$i + 1) . substr(\$decimal_part, 0, \$r_i) . "(" . substr(\$q, \$i + \$r_i + 1) . ")";
}

sub long_primes_five{
my @long_primes;
my @primes = get_primes();
do{
my \$prime = shift @primes;
my \$max_repetend = \$prime - 1;
my \$repeats = true if(\$prime != 2 && \$prime != 5);
if(\$repeats){
my \$x = divide(1, \$prime, [], []);
\$x =~ m/\((\d+)\)/;
my \$repetend = \$1;
push @long_primes, [\$prime, \$x] if length(\$repetend) == \$prime - 1;
}
}while(@long_primes < 5);
return @long_primes;
}

MAIN:{
for my \$p (long_primes_five()){
print \$p-> . "\t" . \$p-> . "\n";
}
}
``````

### Sample Run

``````
\$ perl perl/ch-2.pl
7       0.(142857)
17      0.(0588235294117647)
19      0.(052631578947368421)
23      0.(0434782608695652173913)
29      0.(0344827586206896551724137931)
``````

### Notes

This second part of the challenge was much more fun! Maybe my favorite part was that it largely re-used code from challenge 106 and also Challenge 015. Here we grab a list of pre-computed primes and then check each one for the desired property. After we find five, as required, we're done.

## References

Jort Sort

Long Prime

Challenge 139

posted at: 16:34 by: Adam Russell | path: /perl | permanent link to this entry