From 875d5a2ca4e4be888a9041ef1c395e8316918b19 Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Thu, 21 Jul 2022 17:57:44 +0800
Subject: faster alt2-ch-1.pl

---
 challenge-174/steve-g-lynn/perl/alt2-ch-1.pl | 34 ++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100755 challenge-174/steve-g-lynn/perl/alt2-ch-1.pl

diff --git a/challenge-174/steve-g-lynn/perl/alt2-ch-1.pl b/challenge-174/steve-g-lynn/perl/alt2-ch-1.pl
new file mode 100755
index 0000000000..c58be4e80c
--- /dev/null
+++ b/challenge-174/steve-g-lynn/perl/alt2-ch-1.pl
@@ -0,0 +1,34 @@
+#!/usr/bin/env perl
+
+#real	0m1.660s
+#user	0m1.652s
+#sys	0m0.005s
+
+#faster algorithm. 
+#See my blog: https://thiujiac.blogspot.com/2022/07/pwc-174.html
+
+for my $i (0 .. 9) { print "$i\n"; }
+for my $i (2 .. 650_000 ) { &disarium($i) && (print &disarium($i),"\n" ); }
+
+sub disarium {
+	#-- inputs
+	my ($n)=@_;
+	my (@nstr)=split(//,$n);
+	my @indx = 2..(scalar(@nstr)+1);
+	my $retval=0;
+	
+	#-- calculate a^2+b^3+c^4 ... for $n=abc...
+	for my $i (0..(@nstr-1)) {
+	    $retval += ($nstr[$i] ** $indx[$i]);
+  	}
+  	
+  	#check if $retval is divisible by 10^length($n)-1
+  	my $x = (10 ** @nstr) - 1;
+  	
+  	#if divisible construct and return disarium number
+  	if ( ( ($retval-$n) % $x ) == 0 && (($retval-$n) > 0) ) {
+  		return int( ($retval-$n)/$x ) . $n;
+  	} 
+  	return undef;
+}
+
-- 
cgit