Perl Weekly Challenge 326: Happy Birthday Ma’!

This post presents my solutions to the Perl Weekly Challenge 326.
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:
The PL/Perl implementations are very similar to a pure Perl implementation, even if the PostgreSQL environment could involve some more constraints. Similarly, the PL/PgSQL implementations help me keeping my PostgreSQL programming skills in good shape.

Raku Implementations

PWC 326 - Task 1 - Raku Implementation

The first task was about to find out the day of the year of a given date, in the format yyyy-mm-dd. 

sub MAIN( Str $date ) {
    my $day = Date.new: $date;
    say 1 + $day - Date.new: month => 1, day => 1, year => $day.year;
}


Given the string, it is simple enough to convert it into a Date object and then to compute the difference in days with the first date of the year.

PWC 326 - Task 2 - Raku Implementation

Given an array of integer, compact it so that the first item is repeated the number of times of the second item, and so on. 

sub MAIN( *@nums where { @nums.grep( * ~~ Int ).elems == @nums.elems } ) {
    my @result;
    for @nums -> $base, $times {
		@result.push: ( $base xx $times );
    }

    @result.flat.say;
}


Thanks to the xx list operator, it is very simple to create a list out of the $base knowing how many $times it has to be repeated.

PL/Perl Implementations

PWC 326 - Task 1 - PL/Perl Implementation

Even simpler than the Raku solution, since DateTime provides a specific method to get the day_of_year. Note that there is the need to run it as plperlu because the usage of DateTime module. 

CREATE OR REPLACE FUNCTION
pwc326.task1_plperl( text )
RETURNS int
AS $CODE$

   use DateTime;
   my ( $date ) = @_;

   if ( $date =~ / ^ (\d{4}) - (\d{2}) - (\d{2}) $ /x ) {

      my $day = DateTime->new( year  => $1,
                               month => $2,
   			    day   => $3 );

      return $day->day_of_year;
   }

   return 0;
$CODE$
LANGUAGE plperlu;


PWC 326 - Task 2 - PL/Perl Implementation

The idea is the same as in Raku implementation, but I use a for loop to provide the sublists. 

CREATE OR REPLACE FUNCTION
pwc326.task2_plperl( int[] )
RETURNS SETOF int
AS $CODE$

   my ( $nums ) = @_;
   my @result;

   for my $index ( 0 .. $nums->@* - 2 ) {
       next unless ( $index % 2 == 0 );
      my ( $base, $times ) = $nums->@[ $index .. $index + 1 ];
      push @result, $base for ( 0 .. $times );

   }

   return [ @result ];

$CODE$
LANGUAGE plperl;


PostgreSQL Implementations

PWC 326 - Task 1 - PL/PgSQL Implementation

A single query can do the trick. 

CREATE OR REPLACE FUNCTION
pwc326.task1_plpgsql( d date )
RETURNS int
AS $CODE$
   SELECT 1 +
          d -
	  ( extract( year from d ) || '-01-01' )::date;
$CODE$
LANGUAGE sql;


PWC 326 - Task 2 - PL/PgSQL Implementation

Similar to the PL/Perl implementation. 

CREATE OR REPLACE FUNCTION
pwc326.task2_plpgsql( nums int[] )
RETURNS SETOF int
AS $CODE$
DECLARE
	i int;
	base int;
	times int;
BEGIN

	FOR i IN 1 .. array_length( nums, 1 ) - 1 LOOP
	    IF mod( i, 2 ) = 0 THEN
	       CONTINUE;
	    END IF;

	    base  := nums[ i ];
	    times := nums[ i + 1 ];


	    FOR j in 1 .. times LOOP
	    	RETURN NEXT base;
            END LOOP;
	END LOOP;

RETURN;
END
$CODE$
LANGUAGE plpgsql;


Java Implementations

PWC 326 - Task 1 - PostgreSQL PL/Java Implementation

Since I don’t know enought about the “new” Java timing classes, I use the bovine approach of computing the milliseconds and converting them to days. 

    public static final int task1_pljava( Date day ) throws SQLException {
		logger.log( Level.INFO, "Entering pwc326.task1_pljava" );

		Calendar end   = Calendar.getInstance();
		end.setTime( day );
		Calendar begin = (Calendar) end.clone();
		begin.set( Calendar.DAY_OF_YEAR, 1 );
		return (int) ( ( end.getTimeInMillis() - begin.getTimeInMillis() ) / ( 1000 * 60 * 60 * 24 ) );
    }


PWC 326 - Task 2 - PostgreSQL PL/Java Implementation

An iterative approach. 

    public static final int[] task2_pljava( int[] nums ) throws SQLException {
		logger.log( Level.INFO, "Entering pwc326.task2_pljava" );

		List<Integer> result = new LinkedList<Integer>();
		for( int i = 0; i < nums.length - 1; i++ ) {
		    if( i % 2 != 0 )
				continue;

		    int base  = nums[ i ];
		    int times = nums[ i + 1 ];

		    for ( int j = 0; j < times; j++ )
				result.add( base );
		}

		int r[] = new int[ result.size() ];
		for ( int i = 0; i < result.size(); i++ )
		    r[ i ] = result.get( i );

		return r;
    }


Python Implementations

PWC 326 - Task 1 - Python Implementation

It is only a matter of computing the diff between dates. 

import sys
from datetime import datetime, date

# task implementation
# the return value will be printed
def task_1( args ):
    begin = datetime.strptime( args[ 0 ], "%Y-%m-%d").date()
    end   = date( begin.year, 1, 1 )
    return abs( ( end - begin ).days )


# invoke the main without the command itself
if __name__ == '__main__':
    print( task_1( sys.argv[ 1: ] ) )


PWC 326 - Task 2 - Python Implementation

Similar to the PL/Java implementation. 

import sys

# task implementation
# the return value will be printed
def task_2( args ):
    nums = list( map( int, args ) )

    result = []

    for i in range( 0, len( nums ) - 1 ):
        if i % 2 != 0 :
            continue

        base  = nums[ i ]
        times = nums[ i + 1 ]

        for x in range(0, times ):
            result.append( base )

    return result


# invoke the main without the command itself
if __name__ == '__main__':
    print( task_2( sys.argv[ 1: ] ) )


The article Perl Weekly Challenge 326: Happy Birthday Ma'! has been posted by Luca Ferrari on June 18, 2025

Tags: raku , perlweeklychallenge , perl , python , java