Merge pull request #4082 from lakpatashi/challenge-022

Finished challenge-022 ch-1 only with perl

2 files changed, 59 insertions, 0 deletions

diff --git a/challenge-022/lakpatashi/README b/challenge-022/lakpatashi/README
new file mode 100644
index 0000000000..bc153bd576
--- /dev/null
+++ b/challenge-022/lakpatashi/README
@@ -0,0 +1 @@
+Solution by lakpatashi
diff --git a/challenge-022/lakpatashi/perl/ch-1.pl b/challenge-022/lakpatashi/perl/ch-1.pl
new file mode 100755
index 0000000000..d6108c3fbb
--- /dev/null
+++ b/challenge-022/lakpatashi/perl/ch-1.pl
@@ -0,0 +1,58 @@
+#!/usr/bin/perl
+use POSIX;
+use strict;
+use warnings;
+use List::Util qw( min max sum);
+use feature qw(switch);
+
+my $m = 1000;			# max value for prime list
+my @primes = buildPrimes($m);
+
+my ($first,$second,$count) = (0,1,0);
+for $first (0..$#primes-1){
+	#print "$first ";
+	my $diff = $primes[$second] - $primes[$first];
+	last if $second == $#primes or $count==6;
+	#print "$primes[$first]  $primes[$second] :: ";
+	
+	given($diff){
+		when(6){
+			print "$primes[$first]  $primes[$second]\n";
+			#print "ok\n";
+			$first++;
+			$second++;
+			$count++;
+		}
+		when($diff<6){
+			$second++;
+		}
+		default{
+			$first++;
+		}
+	}
+}
+
+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
+	my $n = shift;
+	my $nSq = sqrt $n;
+	for my $i (@primes){
+		last if $i>$nSq;
+		return 0 unless $n % $i;
+	}
+	return 1;
+}