Merge pull request #4649 from kjetillll/kjetillll-ugly-numbers

my contrib

2 files changed, 55 insertions, 0 deletions

diff --git a/challenge-123/kjetillll/perl/ch-1.pl b/challenge-123/kjetillll/perl/ch-1.pl
new file mode 100755
index 0000000000..fcede75fdc
--- /dev/null
+++ b/challenge-123/kjetillll/perl/ch-1.pl
@@ -0,0 +1,30 @@
+#!/usr/bin/env perl
+
+# Prints the Nth ugly number given by the first command line argument.
+# An ugly number is an integer factorized only by 2, 3 and 5s and no
+# other primes where 1 is considered the first ugly number.
+#
+# sub is_ugly return 1 (true) for ugly integers and 0 (false) otherwise.
+# sub nth_ugly returns the Nth ugly number by recursion.
+#
+# Linux command line test:
+# for n in {1..30}; do echo -n "$n  "; perl ch-1.pl $n; done
+# Outputs the first 30 which is:
+# 1 2 3 4 5 6 8 9 10 12 15 16 18 20 24 25 27 30 32 36 40 45 48 50 54 60 64 72 75 80
+
+sub is_ugly {
+    my $n=shift;
+    $n != int$n                   ? 0
+   :$n == 1                       ? 1
+   :( grep is_ugly($n/$_),2,3,5 ) ? 1
+   :                                0
+}
+
+sub nth_ugly {
+    my($n,$try)=(@_,0);
+    $n ? nth_ugly( $n - is_ugly(++$try), $try) : $try
+}
+
+my($N)=@ARGV;
+
+print nth_ugly( $N ), "\n";
diff --git a/challenge-123/kjetillll/perl/ch-2.pl b/challenge-123/kjetillll/perl/ch-2.pl
new file mode 100644
index 0000000000..c3b8be3be3
--- /dev/null
+++ b/challenge-123/kjetillll/perl/ch-2.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/env perl
+
+#Returns true if four points form a square.
+
+# is_square( [10,20], [20,20], [20,10], [10,10] )  #return 1 (true)
+# is_square( [2,6], [5,1], [0,-2], [-3,3] )        #return 1 (true)
+
+# perl ch-2.pl 2,6 5,1 0,-2 -3,3     #prints 1
+
+sub is_square {
+    die if @_ != 4 or grep@$_!=2,@_;
+    my %dsf;   #dsf=distance squared found
+    for my $p1 ( 0     .. 2 ){       # for the three first points
+    for my $p2 ( $p1+1 .. 3 ){       # loop through the rest of the points
+	my($p1x,$p1y,$p2x,$p2y)=(@{$_[$p1]},@{$_[$p2]});
+	$dsf{ ($p1x-$p2x)**2 + ($p1y-$p2y)**2 }++; #register distance squared
+    }}
+    #If only two different distances found between any two points it means
+    #they form a square, returns 1 (true) if so, or 0 (false) otherwise.
+    #Counting distances squared saves having to do square root as in Pythagoras
+    #grep > 0 prevents two pairs of duplicate points or four equal points from returning true
+    2==(grep$_>0,keys%dsf) ? 1 : 0
+}
+
+print is_square( map[split/,/],@ARGV ), "\n";