Merge pull request #6489 from steve-g-lynn/branch-for-challenge-174

fast PDL::PP solution

1 files changed, 49 insertions, 0 deletions

diff --git a/challenge-174/steve-g-lynn/perl/ch-1-pp.pl b/challenge-174/steve-g-lynn/perl/ch-1-pp.pl
new file mode 100755
index 0000000000..5ada3df755
--- /dev/null
+++ b/challenge-174/steve-g-lynn/perl/ch-1-pp.pl
@@ -0,0 +1,49 @@
+#!/usr/bin/env perl
+
+#real	0m0.480s
+#user	0m1.139s
+#sys	0m0.055s
+
+#-- PDL solution using inline PP
+
+use PDL;
+use PDL::NiceSlice;
+use PDL::AutoLoader;
+
+use Inline 'Pdlpp';
+
+
+#-- now find the sequence by checking ints up to 3_000_000
+
+my $pdl=sequence(long, 3_000_000);
+my $out= $pdl->get_poly;
+print $pdl->where($pdl==$out),"\n";
+
+#[0 1 2 3 4 5 6 7 8 9 89 135 175 518 598 1306 1676 2427 2646798]
+
+__END__
+
+__Pdlpp__
+
+pp_addhdr('
+#include "math.h"
+');
+
+
+#-- the below code used ideas from Laurent Rosenfeld's C solution
+#-- https://github.com/manwar/perlweeklychallenge-club/blob/master/challenge-174/laurent-rosenfeld/c/ch-1.c
+
+pp_def('get_poly',
+	Pars => 'a(); [o]b()',
+	Code => q{
+		int mya = $a();
+		int mya_length = ( (mya <= 9) ? 1 : (floor(log10($a()))+1) );
+		$b()=0;
+		while (mya > 0) {
+			$b()+= pow(mya % 10, mya_length);
+			mya /= 10;
+			mya_length--;
+		}
+	}
+);
+