Practical numbers: Difference between revisions
Added Perl
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</pre>
=={{header|Perl}}==
{{libheader|ntheory}}
<lang perl>use strict;
use warnings;
use feature 'say';
use enum <False True>;
use ntheory <divisors vecextract>;
use List::AllUtils <sum uniq firstidx>;
sub proper_divisors {
return 1 if 0 == (my $n = shift);
my @d = divisors($n);
pop @d;
@d
}
sub powerset_sums { uniq map { sum vecextract(\@_,$_) } 1..2**@_-1 }
sub is_practical {
my($n) = @_;
return True if $n == 1;
return False if 0 != $n % 2;
($n-2 == firstidx { $_ == $n-1 } powerset_sums(proper_divisors($n)) ) ? True : False;
}
my @pn;
is_practical($_) and push @pn, $_ for 1..333;
say @pn . " matching numbers:\n" . (sprintf "@{['%4d' x @pn]}", @pn) =~ s/(.{40})/$1\n/gr;
say '';
printf "%6d is practical? %s\n", $_, is_practical($_) ? 'True' : 'False' for 666, 6666, 66666;</lang>
{{out}}
<pre>77 matching numbers:
1 2 4 6 8 12 16 18 20 24
28 30 32 36 40 42 48 54 56 60
64 66 72 78 80 84 88 90 96 100
104 108 112 120 126 128 132 140 144 150
156 160 162 168 176 180 192 196 198 200
204 208 210 216 220 224 228 234 240 252
256 260 264 270 272 276 280 288 294 300
304 306 308 312 320 324 330
666 is practical? True
6666 is practical? True
66666 is practical? False</pre>
=={{header|Phix}}==
{{trans|Python|(the composition of functions version)}}
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