HEADLINE
Happy Independence Day to all my fellow Indians
This week tasks are once again fun and challenging. Keeping the balance is very difficult, I must admit.
but I am trying …
For the first time, I have joined the private Early Bird Club and taking the advantage of doing the challenge before the launch. I am not sure, if you noticed, this I shared by solutions before lunch time on day one. I did both tasks in Perl, Raku and Swift. I really wanted to add Java to the list as well but then dropped the at the last moment and took day off instead. But that doesn’t mean, I won’t attempt again in the coming weeks.
Having done Raku for some time now, I am getting the hang of it. In fact, I am enjoying it to be honest. I no longer ask stupid Raku questions on the official Twitter handle. Instead I rely on my notes that I have been collecting all along. They are very handy when I am stuck. Another thing that helped me a lot is the Live Video Raku Review by Andrew Shitov. I learnt a lot by watching how he test the code. He makes difficult things easier to understand.
You really don’t want to miss Andrew Shitov weekly review …
I have been coding in Perl for over 20 years now but I noticed there is a clarity in my coding style, thanks to “The Weekly Challenge”. I have never liked my own code so much before. But now every time, I read my past solutions to the weekly challenge, I fall in love again. Doing unit test every week with the regulary solution also made a big difference how I design my solution. Because I do unit test in Raku, I get so much ideas by doing weekly tasks in Raku.
If you are interested then please checkout my Swift solutions to this week tasks.
1) Min Sliding Windows
2) Smallest Neighbour
Last but not the least, I would love hear your view/opinion with regard to anything I do. Please get in touch with me by email: mohammad.anwar@yahoo.com.
Let me share my solutions to the The Weekly Challenge - 073.
TASK #1 › Min Sliding Window
Submitted by Mohammad S Anwar
You are given an array of integers @A and sliding window size $S.
Write a script to create an array of min from each sliding window.
The best part of this task was to create a sliding window. I had lots of fun playing with it. Rest of the job was done by the min() of the cool CPAN module List::Util. I have never used min() with map {} before. Doing weekly challenges, gave me complete freedom to express myself. I fear no one, literally.
sub min_sliding_window {
my ($list, $size) = @_;
die "ERROR: Missing list.\n"
unless defined $list;
die "ERROR: Invalid list [$list].\n"
unless ($list =~ /^[\-?\d\,?\s?]+$/);
$list =~ s/\s//g;
$list = [ split /\,/, $list ];
die "ERROR: Missing size.\n"
unless defined $size;
die "ERROR: Invalid size [$size].\n"
unless (($size >= 2) && ($size - 1 <= $#$list));
my $index = 0;
my @min_sliding_window = ();
while ($index + $size - 1 <= $#$list) {
push @min_sliding_window,
min ( map { $list->[$_] } $index .. $index + $size - 1 );
$index++;
}
return \@min_sliding_window;
}
Doing the same in Raku was not any less fun either.
Doing the one-liner like below gave me immense pleasure.
my $window = $l.[$index .. $index + $size - 1].map: { .Int };
I can’t even imagine writing the above line few months ago.
I want to stay foccussed and keep learning.
sub min-sliding-window(Str $list is copy, Int $size) {
die "ERROR: Invalid list [$list].\n"
unless $list ~~ /^[\-?\d\,?\s?]+$/;
say $list;
$list ~~ s:g/\s//;
my $l = [ $list.split(',') ];
die "ERROR: Invalid size [$size].\n"
unless $size >= 2 && $size - 1 <= $l.elems;
my $index = 0;
my @min-sliding-window = Empty;
while $index + $size - 1 < $l.elems {
my $window = $l.[$index .. $index + $size - 1].map: { .Int };
@min-sliding-window.push: min($window);
$index++;
}
return @min-sliding-window;
}
Having done all the hard work above, time to stich together to solve the task.
I loved the line below:
print join ("\n", (join ', ', @{min_sliding_window($A, $S)}), "");
before I would have done something like this:
print join ', ', @{min_sliding_window($A, $S)}), "\n";
I hate putting \n at the end of print statement. I miss Raku lovely say() :-(
use strict;
use warnings;
use List::Util qw(min);
my $A = $ARGV[0] || "1, 5, 0, 2, 9, 3, 7, 6, 4, 8";
my $S = $ARGV[1] || 3;
print "$A\n";
print join ("\n", (join ', ', @{min_sliding_window($A, $S)}), "");
Raku simply showing off now in the following solution.
use v6.d;
sub MAIN(Str :$A = "1, 5, 0, 2, 9, 3, 7, 6, 4, 8",
Int :$S = 3) {
min-sliding-window($A, $S).join(", ").say;
}
Once again, I am relying on Test2::V0 for my unit test solution. I created package MinSlidingWindow to keep it compact.
package MinSlidingWindow;
use Moo;
use List::Util qw(min);
sub generate {
my ($self, $list, $size) = @_;
die "ERROR: Missing list.\n"
unless defined $list;
die "ERROR: Invalid list [$list].\n"
unless ($list =~ /^[\-?\d\,?\s?]+$/);
$list =~ s/\s//g;
$list = [ split /\,/, $list ];
die "ERROR: Missing size.\n"
unless defined $size;
die "ERROR: Invalid size [$size].\n"
unless (($size >= 2) && ($size - 1 <= $#$list));
my $index = 0;
my @min_sliding_window = ();
while ($index + $size - 1 <= $#$list) {
push @min_sliding_window,
min ( map { $list->[$_] } $index .. $index + $size - 1 );
$index++;
}
return \@min_sliding_window;
}
package main;
use Test2::V0 -target => 'MinSlidingWindow';
my $list = "1, 5, 0, 2, 9, 3, 7, 6, 4, 8";
my %test_cases = (
2 => "1, 0, 0, 2, 3, 3, 6, 4, 4",
3 => "0, 0, 0, 2, 3, 3, 4, 4",
4 => "0, 0, 0, 2, 3, 3, 4",
5 => "0, 0, 0, 2, 3, 3",
6 => "0, 0, 0, 2, 3",
7 => "0, 0, 0, 2",
8 => "0, 0, 0",
9 => "0, 0",
10 => "0",
);
warn "List = $list\n";
foreach my $size (sort { $a <=> $b } keys %test_cases) {
my $min = join ", ", @{$CLASS->generate($list, $size)};
is $min, $test_cases{$size}, "testing window size $size";
}
done_testing;
Here Raku is simply behaving like a good boy and getting the work done.
use Test;
my $list = "1, 5, 0, 2, 9, 3, 7, 6, 4, 8";
my %test-cases = (
2 => "1, 0, 0, 2, 3, 3, 6, 4, 4",
3 => "0, 0, 0, 2, 3, 3, 4, 4",
4 => "0, 0, 0, 2, 3, 3, 4",
5 => "0, 0, 0, 2, 3, 3",
6 => "0, 0, 0, 2, 3",
7 => "0, 0, 0, 2",
8 => "0, 0, 0",
9 => "0, 0",
10 => "0",
);
for %test-cases.keys.sort({ $^a <=> $^b }) -> $size {
is min-sliding-window($list, $size.Int).join(", "),
%test-cases{$size},
"testing size $size";
}
done-testing;
TASK #2 › Smallest Neighbour
Submitted by Mohammad S Anwar
You are given an array of integers @A.
Write a script to create an array that represents the smallest element to the left of each corresponding index. If none found then use 0.
This task got few Team PWC members confused. I blame myself for the confusion, the explanation was not good enough. I had to make few changes to get the message clearly. I am glad it ended up on happy note. In this task also I am mixing the power of min() and map{}.
sub smallest_neighbour {
my ($list) = @_;
die "ERROR: Missing list.\n"
unless defined $list;
die "ERROR: Invalid list [$list].\n"
unless ($list =~ /^[\s?\-?\d\,?\s?]+$/);
$list =~ s/\s//g;
$list = [ split /\,/, $list ];
my @smallest_neighbour = (0);
foreach my $i (1 .. $#$list) {
my $min = min( map { $list->[$_] } 0..$i-1 );
push @smallest_neighbour, ($min < $list->[$i])?($min):(0);
}
return \@smallest_neighbour;
}
The best line in the Raku solution is below:
my $min = min( $l.[0 .. $i - 1].map: { .Int } );
Other than that, rest is plain Raku magic.
sub smallest-neighbour(Str $list is copy) {
die "ERROR: Invalid list [$list].\n"
unless $list ~~ /^[\s?\-?\d\,?\s?]+$/;
$list ~~ s:g/\s//;
my $l = [ $list.split(',') ];
my @smallest_neighbour = 0;
for 1 .. $l.elems - 1 -> $i {
my $min = min( $l.[0 .. $i - 1].map: { .Int } );
@smallest_neighbour.push: ($min < $l.[$i]) ?? ($min) !! (0);
}
return @smallest_neighbour;
}
It is time for Perl to show off.
use strict;
use warnings;
use List::Util qw(min);
my $A = $ARGV[0] || "7, 8, 3, 12, 10";
print "$A\n";
print join("\n", (join ', ', @{smallest_neighbour($A)}), "");
Raku is not far off either.
use v6.d;
sub MAIN(Str $list = "7, 8, 3, 12, 10") {
say $list;
smallest-neighbour($list).join(', ').say;
}
Perl unit test solution with the power of Test2::V0.
package SmallestNeighbour;
use Moo;
use List::Util qw(min);
sub fetch {
my ($self, $list) = @_;
die "ERROR: Missing list.\n"
unless defined $list;
die "ERROR: Invalid list [$list].\n"
unless ($list =~ /^[\s?\-?\d\,?\s?]+$/);
$list =~ s/\s//g;
$list = [ split /\,/, $list ];
my @smallest_neighbour = (0);
foreach my $i (1 .. $#$list) {
my $min = min( map { $list->[$_] } 0..$i-1 );
push @smallest_neighbour, ($min < $list->[$i])?($min):(0);
}
return \@smallest_neighbour;
}
package main;
use Test2::V0 -target => 'SmallestNeighbour';
my %test_cases = (
"7, 8, 3, 12, 10" => "0, 7, 0, 3, 3",
"0, 1, 5, 2, 3" => "0, 0, 0, 0, 0",
"1, -2, 7, 5, -4" => "0, 0, -2, -2, 0",
);
foreach my $list (sort keys %test_cases) {
my $min = join ", ", @{$CLASS->fetch($list)};
is $min, $test_cases{$list}, "testing list $list";
}
done_testing;
Raku is keeping it simple and clean.
use Test;
my %test-cases = (
"7, 8, 3, 12, 10" => "0, 7, 0, 3, 3",
"0, 1, 5, 2, 3" => "0, 0, 0, 0, 0",
"1, -2, 7, 5, -4" => "0, 0, -2, -2, 0",
);
for %test-cases.keys.sort -> $list {
is smallest-neighbour($list).join(', '),
%test-cases{$list},
"testing list $list";
}
done-testing;
That’s it for this week. Speak to you soon.