From 3d271507b2ad90a357fb128df8fcf47b66f91ffb Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Sat, 11 Jun 2022 21:03:20 +0800
Subject: improved perl ch-2.pl

---
 challenge-168/steve-g-lynn/perl/ch-2.pl | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/challenge-168/steve-g-lynn/perl/ch-2.pl b/challenge-168/steve-g-lynn/perl/ch-2.pl
index d1f6f0aced..4732c9b136 100755
--- a/challenge-168/steve-g-lynn/perl/ch-2.pl
+++ b/challenge-168/steve-g-lynn/perl/ch-2.pl
@@ -1,13 +1,17 @@
 #!/usr/bin/perl
 
-use Math::Prime::XS qw(is_prime sieve_primes);
-
+use Math::Prime::XS qw(is_prime);
 
+print &home_prime(10),"\n";
+#773
 print &home_prime(16),"\n";
-#-- should be 31636373 [wikipedia example]
+#31636373
+print &home_prime(20),"\n";
+#3318308475676071413
 
 sub home_prime {
-	local ($n)=@_;
+	my ($n)=@_;
+	is_prime($n) && return $n;
 	while (1){
 		$n=&factors($n);
 		(is_prime($n)) && last;
@@ -18,20 +22,25 @@ sub home_prime {
 
 sub factors {
 	#--return concatenated prime factors of a number n 
-	local ($n)=@_;
-	local @primes=sieve_primes($n);
-	local $retstring="";
+	my ($n)=@_;
+	local $sqrt_n=int(sqrt($n));
+
+	my $retstring="";
 	
 	if (is_prime($n)){
 		return $n;
 	}
 	else {
-		foreach $prime (sort{$a<=>$b} @primes){
+		for $prime (2 .. $sqrt_n){
+		#-- no need to get primes first
+		#-- routine automatically finds only prime factors
 			while ( ($n % $prime) == 0){
 				$n /= $prime;
 				$retstring .= $prime;
 			}
+			(is_prime($n)) && last; 
 		}
+		($n > 1) && ($retstring .= $n);
 	}
 	return $retstring;	
 }
-- 
cgit 


From 5182b192585848d1b91afce11d151906762d9bcd Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Sat, 11 Jun 2022 21:07:19 +0800
Subject: improved ch-2.pl

---
 challenge-168/steve-g-lynn/perl/ch-2.pl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/challenge-168/steve-g-lynn/perl/ch-2.pl b/challenge-168/steve-g-lynn/perl/ch-2.pl
index 4732c9b136..4fcc0e19dd 100755
--- a/challenge-168/steve-g-lynn/perl/ch-2.pl
+++ b/challenge-168/steve-g-lynn/perl/ch-2.pl
@@ -9,6 +9,7 @@ print &home_prime(16),"\n";
 print &home_prime(20),"\n";
 #3318308475676071413
 
+
 sub home_prime {
 	my ($n)=@_;
 	is_prime($n) && return $n;
-- 
cgit 


From 337a373ae28cb51b8d74be6505b2f695e5ac2cb5 Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Sat, 11 Jun 2022 21:10:58 +0800
Subject: improved perl ch-2.pl

---
 challenge-168/steve-g-lynn/perl/ch-2.pl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/challenge-168/steve-g-lynn/perl/ch-2.pl b/challenge-168/steve-g-lynn/perl/ch-2.pl
index 4fcc0e19dd..67db0846ea 100755
--- a/challenge-168/steve-g-lynn/perl/ch-2.pl
+++ b/challenge-168/steve-g-lynn/perl/ch-2.pl
@@ -10,6 +10,7 @@ print &home_prime(20),"\n";
 #3318308475676071413
 
 
+
 sub home_prime {
 	my ($n)=@_;
 	is_prime($n) && return $n;
@@ -21,6 +22,7 @@ sub home_prime {
 }
 
 
+
 sub factors {
 	#--return concatenated prime factors of a number n 
 	my ($n)=@_;
-- 
cgit 


From ff980517b9e50ee68b469cddc0ca26e5f9982cee Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Sat, 11 Jun 2022 21:20:08 +0800
Subject: improved ch-2.pl

---
 challenge-168/steve-g-lynn/perl/ch-2.pl | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/challenge-168/steve-g-lynn/perl/ch-2.pl b/challenge-168/steve-g-lynn/perl/ch-2.pl
index 67db0846ea..be079624bc 100755
--- a/challenge-168/steve-g-lynn/perl/ch-2.pl
+++ b/challenge-168/steve-g-lynn/perl/ch-2.pl
@@ -9,8 +9,6 @@ print &home_prime(16),"\n";
 print &home_prime(20),"\n";
 #3318308475676071413
 
-
-
 sub home_prime {
 	my ($n)=@_;
 	is_prime($n) && return $n;
@@ -21,12 +19,10 @@ sub home_prime {
 	return $n;
 }
 
-
-
 sub factors {
 	#--return concatenated prime factors of a number n 
 	my ($n)=@_;
-	local $sqrt_n=int(sqrt($n));
+	local $sqrt_n=floor(sqrt($n));
 
 	my $retstring="";
 	
-- 
cgit 


From bfba759aa6812adf1536870315cc6648b97163c5 Mon Sep 17 00:00:00 2001
From: Stephen Lynn <bizlsg@localhost.localdomain>
Date: Sat, 11 Jun 2022 21:45:00 +0800
Subject: improved ch-2.pl

---
 challenge-168/steve-g-lynn/perl/ch-2.pl | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/challenge-168/steve-g-lynn/perl/ch-2.pl b/challenge-168/steve-g-lynn/perl/ch-2.pl
index be079624bc..5fe95544ad 100755
--- a/challenge-168/steve-g-lynn/perl/ch-2.pl
+++ b/challenge-168/steve-g-lynn/perl/ch-2.pl
@@ -4,8 +4,10 @@ use Math::Prime::XS qw(is_prime);
 
 print &home_prime(10),"\n";
 #773
+
 print &home_prime(16),"\n";
 #31636373
+
 print &home_prime(20),"\n";
 #3318308475676071413
 
@@ -43,3 +45,6 @@ sub factors {
 	}
 	return $retstring;	
 }
+
+1;
+
-- 
cgit