Perl Weekly Challenge 354: time to drink and wait for the new year!

This post presents my solutions to the Perl Weekly Challenge 354.
I keep doing the Perl Weekly Challenge in order to mantain my coding skills in good shape, as well as in order to learn new things, with particular regard to Raku, a language that I love.
This week, I solved the following tasks:

• PWC 354 - Task 1 - Raku
• PWC 354 - Task 2 - Raku

Raku Implementations

PWC 354 - Task 1 - Raku Implementation

The first task was about finding all the couple of numbers that provide the min difference in a given list.

sub MAIN( *@nums is copy
	  where { @nums.elems %% 2 && @nums.grep( * ~~ Int ).elems == @nums.elems } ) {
    @nums .= sort;
    my %diffs;
    @nums[ 0 .. * - 2].map( { state $i = 0;
			      %diffs{ @nums[ $i + 1 ] - @nums[ $i ] }.push: [ @nums[ $i + 1 ], @nums[ $i ] ];
			      $i++;
			    } );

    %diffs{ %diffs.keys.map( *.Int ).min }.join( "\n" ).say;
}

I do this:

• sort the numbers (in place)
• map all the couples into a %diffs hash where the key is the value of the difference, and the value is an array where I push all the couples with the same difference.

After having done that, I can extract the min key and print out all the couples.

PWC 354 - Task 2 - Raku Implementation

The second task was about shifting a matrix following a few given rules:

• every element moves to its right;
• a line wraps to the next one;
• the last element wraps to the first.

I provide the application with all the given values in @matrix and with $k as the number of shits.

sub MAIN() {
    my @matrix = [1, 2, 3],
                 [4, 5, 6],
                 [7, 8, 9];
    my $k = 1;

    @matrix = [1, 2],
                  [3, 4],
                  [5, 6];
    $k = 1;

    @matrix = [1, 2, 3],
              [4, 5, 6];
    $k = 5;

    my @next;
    while ( $k ) {
		for 0 ..^ @matrix.elems -> $row {
		    if ( $row == 0 ) {
				@next[ $row ].push: @matrix[ * - 1 ][ * - 1 ];  # element at 0, 0
				@next[ $row ].push: |@matrix[ $row ][ 0 .. * - 2 ]; # first row
		    }
		    else {
				@next[ $row ].push: @matrix[ $row - 1 ][ * - 1 ];
				@next[ $row ].push: |@matrix[ $row  ][ 0 .. * - 2 ];
		    }
		}

		$k--;
		if ( $k ) {
		    @matrix = @next;
		    @next = ();
		}
    }


    say @next;
}

The idea is quite simple: iterate on all the $rows of the matrix and, in the case of the first row, construct an ad-hoc row, otherwise build it on the basis of the previous one. Then switch the original matrix with the new one and restart.