3 files changed, 92 insertions, 0 deletions
diff --git a/challenge-023/lakpatashi/README b/challenge-023/lakpatashi/README
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index 0000000000..bc153bd576
--- /dev/null
+++ b/challenge-023/lakpatashi/README
@@ -0,0 +1 @@
+Solution by lakpatashi
diff --git a/challenge-023/lakpatashi/perl/ch-1.pl b/challenge-023/lakpatashi/perl/ch-1.pl
new file mode 100755
index 0000000000..7bc81fef20
--- /dev/null
+++ b/challenge-023/lakpatashi/perl/ch-1.pl
@@ -0,0 +1,42 @@
+#!/usr/bin/perl
+
+use warnings;
+use strict;
+use Data::Dumper;
+use List::Util qw(max min sum);
+use feature qw(switch);
+use Memoize;
+memoize qw (factorial );
+
+#part 1
+# commandline arg ==> order, arr
+my ($order,@arr) = @ARGV;
+if($#ARGV < 0){	#default values when @ARGV is absent
+	@arr = (5, 9, 2, 8, 1, 6);
+	$order = 1;
+}
+print "arr :: @arr\n";
+print "order :: $order\n";
+print "diff :: ";
+for my $i (0..$#arr-$order){
+	print nthDiff( reverse @arr[$i..$i+$order] )," ";
+}
+print "\n";
+
+sub nthDiff{
+	#arr
+	my @arr = @_;
+	@arr = map { (-1)**($_) * binomial($#arr,$_) * $arr[$_]} 0..$#arr;
+	return sum @arr;
+}
+
+sub binomial{
+	my ($n,$r) = @_;
+	return int factorial($n) / ( factorial($r) * factorial($n-$r));
+}
+
+sub factorial{
+	my ($n) = @_;
+	return 1 if $n<1;
+	return $n*factorial($n-1);
+}
diff --git a/challenge-023/lakpatashi/perl/ch-2.pl b/challenge-023/lakpatashi/perl/ch-2.pl
new file mode 100755
index 0000000000..97ac7598fc
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+++ b/challenge-023/lakpatashi/perl/ch-2.pl
@@ -0,0 +1,49 @@
+#!/usr/bin/perl
+use POSIX;
+use strict;
+use warnings;
+use List::Util qw( min max sum);
+
+
+my $m = 1000000;			# max value for prime list
+my @primes = buildPrimes($m);
+my $n = 228;
+for my $i (@primes){
+	last if $n==1;
+	if($i <= sqrt($n)){
+		while(not $n % $i ){
+			print "$i ";
+			$n /= $i;
+		}
+	}else{
+		print "$n ";
+		last;
+	}
+
+}
+
+
+sub buildPrimes{	# building prime list
+	my $m=shift;
+	my @prime = (1)x($m+1);
+	@prime[0,1]=(0)x2;
+	for (my $p=2; $p*$p <= $m; $p++){
+		if($prime[$p]==1){
+			for(my $i= $p*$p; $i<= $m; $i+=$p){
+				$prime[$i]=0;
+			}
+		}
+	}
+	@prime = grep{ $prime[$_] } 2..$m;
+	return @prime;
+}
+
+sub isPrime{			# check primality, not is use
+	my $n = shift;
+	my $nSq = sqrt $n;
+	for my $i (@primes){
+		last if $i>$nSq;
+		return 0 unless $n % $i;
+	}
+	return 1;
+}