diff options
| -rw-r--r-- | challenge-144/wlmb/blog.txt | 1 | ||||
| -rwxr-xr-x | challenge-144/wlmb/perl/ch-1.pl | 23 | ||||
| -rwxr-xr-x | challenge-144/wlmb/perl/ch-2.pl | 27 |
3 files changed, 51 insertions, 0 deletions
diff --git a/challenge-144/wlmb/blog.txt b/challenge-144/wlmb/blog.txt new file mode 100644 index 0000000000..76333f729a --- /dev/null +++ b/challenge-144/wlmb/blog.txt @@ -0,0 +1 @@ +https://wlmb.github.io/2021/12/22/PWC144/ diff --git a/challenge-144/wlmb/perl/ch-1.pl b/challenge-144/wlmb/perl/ch-1.pl new file mode 100755 index 0000000000..c5ce591b0d --- /dev/null +++ b/challenge-144/wlmb/perl/ch-1.pl @@ -0,0 +1,23 @@ +#!/usr/bin/env perl +# Perl weekly challenge 144 +# Task 1: Semiprime +# +# See https://wlmb.github.io/2021/12/22/PWC144/#task-1-semiprime +use v5.12; +use warnings; +use PDL; +use PDL::NiceSlice; +my $N=shift//100; # get upper limit from command line +my $sieve=ones($N+1); #Erastothenes sieve +$sieve(0:1).=0; #0 and 1 are not primes +$sieve($_**2:-1:$_).=0 for(2..sqrt($N)); #remove non-primes +my $primes=$sieve->xvals->where($sieve); +my $pairs=cat($primes, $primes(*))->mv(-1,0); # pairs of primes +my $sp=$pairs->prodover; # semiprimes +my ($p1, $p2, $semiprimes)=where($pairs((0)), $pairs((1)), $sp, + ($sp->xvals>=$sp->yvals)&($sp<100)); +my $indx=$semiprimes->qsorti; # order results +my ($p1_o,$p2_o,$semiprimes_o)=map {$_->($indx)} ($p1, $p2, $semiprimes); +say "The semiprimes not greater than $N are"; +say $semiprimes_o(($_)), "=", $p1_o(($_)), "*", $p2_o(($_)) + foreach 0..$indx->nelem-1; diff --git a/challenge-144/wlmb/perl/ch-2.pl b/challenge-144/wlmb/perl/ch-2.pl new file mode 100755 index 0000000000..cb1e094603 --- /dev/null +++ b/challenge-144/wlmb/perl/ch-2.pl @@ -0,0 +1,27 @@ +#!/usr/bin/env perl +# Perl weekly challenge 144 +# Task 2: Ulam Sequence +# +# See https://wlmb.github.io/2021/12/22/PWC144/#task-2-ulam-sequence +use v5.12; +use warnings; +use PDL; +use PDL::NiceSlice; +say("Usage: ./ch-2.pl u v [N]\nto find the first N (default 10) terms". + " of the Ulam sequence u,v..."),exit unless @ARGV==2 || @ARGV==3; +say("The given numbers should not be equal"), exit unless $ARGV[0]!=$ARGV[1]; +my $ulam=pdl(@ARGV[(0,1)]); # initialize sequence +my $N=$ARGV[2]//10; +foreach(3..$N){ + my $sums=$ulam+$ulam->slice("*"); # addition table for Ulam sequence + my $ordered=$sums->where( + ($sums->xvals>$sums->yvals) # upper triangle in addition table + &($sums>$ulam((-1)) # remove previous terms + ))->qsort; # order + $ordered=$ordered->where( # eliminate duplicates with right or left + ($ordered!=$ordered->rotate(-1)) + &($ordered!=$ordered->rotate(1))) if $ordered->nelem>1; + $ulam=$ulam->append($ordered((0))); +} +say "Input: u=$ARGV[0], v=$ARGV[1]", defined $ARGV[2]?", N=$N":""; +say "Output: $ulam"; |