imported my solution's to challenge 123: 2 easy tasks this time..

3 files changed, 163 insertions, 40 deletions

diff --git a/challenge-123/duncan-c-white/README b/challenge-123/duncan-c-white/README
index 943444f99f..b7d8d96453 100644
--- a/challenge-123/duncan-c-white/README
+++ b/challenge-123/duncan-c-white/README
@@ -1,57 +1,47 @@
-Task 1: "Average of Stream
+Task 1: "Ugly Numbers
 
-You are given a stream of numbers, @N.
+You are given an integer $n >= 1.
 
-Write a script to print the average of the stream at every point.
+Write a script to find the $nth element of Ugly Numbers.
+
+Ugly numbers are those number whose prime factors are 2, 3 or 5.
+For example, the first 10 Ugly Numbers are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12.
 
 Example
 
-Input: @N = (10, 20, 30, 40, 50, 60, 70, 80, 90, ...)
-Output:      10, 15, 20, 25, 30, 35, 40, 45, 50, ...
+	Input: $n = 7
+	Output: 8
 
-Average of first number is 10.
-Average of first 2 numbers (10+20)/2 = 15
-Average of first 3 numbers (10+20+30)/3 = 20
-Average of first 4 numbers (10+20+30+40)/4 = 25 and so on.
+	Input: $n = 10
+	Output: 12
 "
 
-My notes: sounds quite simple, just requires a running total.
-
+My notes: sounds quite simple.  I thought of digging out primes and
+factors code from previous PWCs, but the only primes we care about are
+2, 3 and 5.
 
-Task 2: "Basketball Points
 
-You are given a score $S.
+Task 2: "Square Points
 
-You can win basketball points e.g. 1 point, 2 points and 3 points.
+You are given coordinates of four points
+i.e. (x1, y1), (x2, y2), (x3, y3) and (x4, y4).
 
-Write a script to find out the different ways you can score $S.
+Write a script to find out if the given four points form a square.
 
 Example
 
-Input: $S = 4
-Output: 1 1 1 1
-        1 1 2
-        1 2 1
-        1 3
-        2 1 1
-        2 2
-        3 1
-
-Input: $S = 5
-Output: 1 1 1 1 1
-        1 1 1 2
-        1 1 2 1
-        1 1 3
-        1 2 1 1
-        1 2 2
-        1 3 1
-        2 1 1 1
-        2 1 2
-        2 2 1
-        2 3
-        3 1 1
+	Input: x1 = 10, y1 = 20
+	       x2 = 20, y2 = 20
+	       x3 = 20, y3 = 10
+	       x4 = 10, y4 = 10
+	Output: 1 as the given coordinates form a square.
+
+	Input: x1 = 12, y1 = 24
+	       x2 = 16, y2 = 10
+	       x3 = 20, y3 = 12
+	       x4 = 18, y4 = 16
+	Output: 0 as the given coordinates doesn't form a square.
 "
 
-My notes: Assuming I'm understanding it right, all combinations of
-removing 1, 2 or 3 from N repeatedly.  Easyish (recursive).
-NOTE: surely the $S = 5 example omits one last solution "3 2"?
+My notes: sounds surprisingly easy for a task 2.  I guess the points
+can be in any order.
diff --git a/challenge-123/duncan-c-white/perl/ch-1.pl b/challenge-123/duncan-c-white/perl/ch-1.pl
new file mode 100755
index 0000000000..38fde07b51
--- /dev/null
+++ b/challenge-123/duncan-c-white/perl/ch-1.pl
@@ -0,0 +1,70 @@
+#!/usr/bin/perl
+# 
+# Task 1: "Ugly Numbers
+# 
+# You are given an integer $n >= 1.
+# 
+# Write a script to find the $nth element of Ugly Numbers.
+# 
+# Ugly numbers are those number whose prime factors are 2, 3 or 5.
+# For example, the first 10 Ugly Numbers are 1, 2, 3, 4, 5, 6, 8, 9, 10, 12.
+# 
+# Example
+# 
+# 	Input: $n = 7
+# 	Output: 8
+# 
+# 	Input: $n = 10
+# 	Output: 12
+# "
+# 
+# My notes: sounds quite simple.  I thought of digging out primes and
+# factors code from previous PWCs, but the only primes we care about are
+# 2, 3 and 5.
+# 
+
+use strict;
+use warnings;
+use feature 'say';
+use Function::Parameters;
+#use Data::Dumper;
+
+die "Usage: ugly-number N\n" unless @ARGV == 1;
+my $n = shift;
+die "ugly-number: N ($n) must be >= 1\n" if $n<1;
+
+my $x = nth_ugly( $n );
+say $x;
+
+
+#
+# my $ugly = isugly( $x );
+#	Return 1 iff $x is ugly; return 0 otherwise.
+#
+fun isugly( $x )
+{
+	return 0 if $x < 1;
+	while( $x % 5 == 0 ) { $x /= 5 }
+	while( $x % 3 == 0 ) { $x /= 3 }
+	while( $x % 2 == 0 ) { $x /= 2 }
+	return $x==1 ? 1 : 0;
+}
+
+
+#
+# my $x = nth_ugly( $n );
+#	Determine and result $x, the $n-th ugly number.
+#
+fun nth_ugly( $n )
+{
+	for( my $i=1; ; $i++ )
+	{
+		if( isugly($i) )
+		{
+			if( --$n==0 )
+			{
+				return $i;
+			}
+		}
+	}
+}
diff --git a/challenge-123/duncan-c-white/perl/ch-2.pl b/challenge-123/duncan-c-white/perl/ch-2.pl
new file mode 100755
index 0000000000..5bdd745893
--- /dev/null
+++ b/challenge-123/duncan-c-white/perl/ch-2.pl
@@ -0,0 +1,63 @@
+#!/usr/bin/perl
+# 
+# Task 2: "Square Points
+# 
+# You are given coordinates of four points
+# i.e. (x1, y1), (x2, y2), (x3, y3) and (x4, y4).
+# 
+# Write a script to find out if the given four points form a square.
+# 
+# Example
+# 
+# 	Input: x1 = 10, y1 = 20
+# 	       x2 = 20, y2 = 20
+# 	       x3 = 20, y3 = 10
+# 	       x4 = 10, y4 = 10
+# 	Output: 1 as the given coordinates form a square.
+# 
+# 	Input: x1 = 12, y1 = 24
+# 	       x2 = 16, y2 = 10
+# 	       x3 = 20, y3 = 12
+# 	       x4 = 18, y4 = 16
+# 	Output: 0 as the given coordinates doesn't form a square.
+# "
+# 
+# My notes: sounds surprisingly easy for a task 2.  I guess the points
+# can be in any order.
+# 
+
+use strict;
+use warnings;
+use feature 'say';
+use Function::Parameters;
+use Getopt::Long;
+use Data::Dumper;
+
+my $debug = 0;
+die "Usage: square-points X1 Y2 X2 Y2 X3 Y3 X4 Y4\n" unless
+	GetOptions( "debug" => \$debug ) && @ARGV==8;
+my( $x1, $y1, $x2, $y2, $x3, $y3, $x4, $y4 ) = @ARGV;
+my @p = ( [$x1,$y1], [$x2,$y2], [$x3,$y3], [$x4,$y4] );
+
+#
+# my $square = issquare( @p );
+#	Return 1 iff the 4 points in @p make a square, 0 otherwise.
+#
+fun issquare( @p )
+{
+	# first, let's sort the coordinates by x-first-and-then-y-if-xs-same
+	@p = sort { $a->[0]<=>$b->[0] || $a->[1]<=>$b->[1] } @p;
+
+	#print Dumper \@p;
+
+	return 0 unless $p[0]->[0] == $p[1]->[0];
+	return 0 unless $p[2]->[0] == $p[3]->[0];
+	my $size = $p[1]->[1] - $p[0]->[1];
+	return 0 if $size==0;
+	return 0 unless $p[3]->[1] - $p[2]->[1] == $size;
+	return 1;
+}
+
+
+my $square = issquare( @p );
+say $square;