Week 333 - Straight zeroes

3 files changed, 95 insertions, 0 deletions

diff --git a/challenge-333/peter-campbell-smith/blog.txt b/challenge-333/peter-campbell-smith/blog.txt
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+++ b/challenge-333/peter-campbell-smith/blog.txt
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+http://ccgi.campbellsmiths.force9.co.uk/challenge/333
diff --git a/challenge-333/peter-campbell-smith/perl/ch-1.pl b/challenge-333/peter-campbell-smith/perl/ch-1.pl
new file mode 100755
index 0000000000..f3fbcd4bcc
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+++ b/challenge-333/peter-campbell-smith/perl/ch-1.pl
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+#!/usr/bin/perl
+
+# Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge
+
+use v5.26;    # The Weekly Challenge - 2025-08-04
+use utf8;     # Week 333 - task 1 - Straight line
+use warnings; # Peter Campbell Smith
+binmode STDOUT, ':utf8';
+use Encode;
+
+straight_line([2, 1], [2, 3], [2, 5]);
+straight_line([1, 4], [3, 4], [10, 4]);
+straight_line([0, 0], [1, 1], [2, 3]);
+straight_line([1, 1], [1, 1], [1, 1]);
+straight_line([1000000, 1000000], [2000000, 2000000], [3000000, 3000000]);
+straight_line([0, 0], [1, 1], [99999999, 100000000]);
+straight_line([8, -5], [3, -2], [-2, 1]);
+straight_line([8, -5], [3, -2], [-2, 1], [-7, 4], [-12, 7]);
+straight_line([0, 0], [1, 0], [2, 1], [3, 2]);
+
+sub straight_line {
+	
+	my (@p, $i, $j, @x, @y, $c, $d, $m, $yy, $same, $vertical, $input, $output);
+	
+	# initialise
+	@p = @_;
+	$i = 0;
+	$vertical = $same = 1;
+
+	# loop over points
+	for $i (0 .. $#p) {
+		($x[$i], $y[$i]) = @{$p[$i]};
+		$input .= '[' . sprintf('%d', $x[$i]) . ', ' . sprintf('%d', $y[$i]) . '], ';
+		
+		# check for points being identical or all the same x
+		if ($i > 0) {
+			if ($x[$i] != $x[0] or $y[$i] != $y[0]) {
+				$same = 0;
+				$d = $i;  # a point with diffferent x from x[0]
+			}
+			$vertical = 0 if $x[$i] != $x[0];
+		}
+	}
+	$output = qq[true: any straight line through ($x[0], $y[0])] if $same;
+	$output = qq[true: x = $x[0]] if ($vertical and not $same);
+	
+	# otherwise calculate gradient and offset (using points 0 and d)
+	unless ($output) {
+		$m = 0;
+		$m = ($y[$d] - $y[0]) / ($x[$d] - $x[0]);
+		$c = $y[0] - $m * $x[0];
+		
+		# check that all points fall on y = mx + c
+		for $i (0 .. $#p) {
+			$yy = $m * $x[$i] + $c;
+		if (abs($yy - $y[$i]) > 1e-15) {
+				$output = qq[false: ($x[$i], $y[$i]) is not collinear with points 0 and $d];
+				last;
+			}
+		}
+		
+		# yes they do!
+		$output = qq[true: y = ] . ($m != 0 ? ($m == -1 ? '-x' : ($m != 1 ? "${m}x " : 'x ')) : '') . 
+			($m != 0 ? ($c == 0 ? '' : ($c > 0 ? "+ $c" : '- ' . -$c)) : $c) unless $output;
+	}
+	
+	say qq{\nInput:  \$list = (} . substr($input, 0, -2) . ')';
+	say qq[Output: $output];
+}
diff --git a/challenge-333/peter-campbell-smith/perl/ch-2.pl b/challenge-333/peter-campbell-smith/perl/ch-2.pl
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index 0000000000..60e8c0d02a
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+++ b/challenge-333/peter-campbell-smith/perl/ch-2.pl
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+#!/usr/bin/perl
+
+# Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge
+
+use v5.26;    # The Weekly Challenge - 2025-08-04
+use utf8;     # Week 333 - task 2 - Duplicate zeros
+use warnings; # Peter Campbell Smith
+binmode STDOUT, ':utf8';
+use Encode;
+
+duplicate_zeros(1, 0, 2, 3, 0, 4, 5, 0);
+duplicate_zeros(1, 2, 3);
+duplicate_zeros(1, 2, 3, 0);
+duplicate_zeros(0, 0, 1, 2);
+duplicate_zeros(1, 2, 0, 3, 4);
+
+sub duplicate_zeros {
+	
+	# map each 0 to 0, 0
+	my @output = map($_ == 0 ? (0, 0) : $_, @_);
+	
+	# output as many elements in @output as in the input array
+	say qq[\nInput:  (] . join(', ', @_) . ')';
+	say qq[Output: (] . join(', ', @output[0 .. $#_]) . ')';
+}