laurent_r

These are some answers to the Week 262, Task 1, of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few days from now (on March 31, 2024 at 23:59). This blog post provides some solutions to this challenge. Please don’t read on if you intend to complete the challenge on your own.

Task 1: Max Positive Negative

You are given an array of integers, @ints.

Write a script to return the maximum number of either positive or negative integers in the given array.

Example 1

Input: @ints = (-3, 1, 2, -1, 3, -2, 4)
Output: 4

Count of positive integers: 4
Count of negative integers: 3
Maximum of count of positive and negative integers: 4

Example 2

Input: @ints = (-1, -2, -3, 1)
Output: 3

Count of positive integers: 1
Count of negative integers: 3
Maximum of count of positive and negative integers: 3

Example 3

Input: @ints = (1,2)
Output: 2

Count of positive integers: 2
Count of negative integers: 0
Maximum of count of positive and negative integers: 2

Although this is not clearly specified, we will consider only strictly positive and strictly negative input values (in other words, we will discard values equal to zero).

Max Positive Negative in Raku

We use Raku built-in grep, elems, and max methods to come up with a one-liner solution in Raku.

sub max-pos-neg (@in) {
    (@in.grep({$_ > 0}).elems, @in.grep({$_ < 0}).elems).max;
}

my @tests = <-3 1 2 -1 3 -2 4>, <-1 -2 -3 1>, <1 2>;
for @tests -> @test {
    printf "%-20s => ", "@test[]";
    say max-pos-neg @test;
}

This program displays the following output:

$ raku ./max-pos-neg.raku
-3 1 2 -1 3 -2 4     => 4
-1 -2 -3 1           => 3
1 2                  => 2

Max Positive Negative in Perl

This is a port to Perl of the above Raku program, with the only significant change being that we use the ternary operator (? :) to replace max.

use strict;
use warnings;
use feature 'say';

sub max_pos_neg {
    my $pos_count = scalar grep {$_ > 0} @_;
    my $neg_count = scalar grep {$_ < 0} @_;
    $pos_count > $neg_count ? $pos_count : $neg_count;
}

my @tests = ( [<-3 1 2 -1 3 -2 4>], 
              [<-1 -2 -3 1>], [<1 2>] );
for my $test (@tests) {
    printf "%-20s => ", "@$test";
    say max_pos_neg @$test;
}

This program displays the following output:

$ perl ./max-pos-neg.pl
-3 1 2 -1 3 -2 4     => 4
-1 -2 -3 1           => 3
1 2                  => 2

Wrapping up

The next week Perl Weekly Challenge will start soon. If you want to participate in this challenge, please check https://perlweeklychallenge.org/ and make sure you answer the challenge before 23:59 BST (British summer time) on April 7, 2024. And, please, also spread the word about the Perl Weekly Challenge if you can.