DAJ 333 blogged

1 files changed, 46 insertions, 0 deletions

diff --git a/challenge-333/dave-jacoby/perl/ch-1.pl b/challenge-333/dave-jacoby/perl/ch-1.pl
new file mode 100644
index 0000000000..5772bdb9c3
--- /dev/null
+++ b/challenge-333/dave-jacoby/perl/ch-1.pl
@@ -0,0 +1,46 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use experimental qw{ say state postderef signatures };
+
+my @examples = (
+
+    [ [ 2,       1 ],       [ 2,       3 ],       [ 2,       5 ] ],
+    [ [ 1,       4 ],       [ 3,       4 ],       [ 10,      4 ] ],
+    [ [ 0,       0 ],       [ 1,       1 ],       [ 2,       3 ] ],
+    [ [ 1,       1 ],       [ 1,       1 ],       [ 1,       1 ] ],
+    [ [ 1000000, 1000000 ], [ 2000000, 2000000 ], [ 3000000, 3000000 ] ],
+);
+
+for my $input (@examples) {
+    my $output = straight_line( $input->@* );
+    my $str = join ',', map { qq{[$_]} } map { join ', ', $_->@* } $input->@*;
+    say <<"END";
+    Input:  \@str = ($str)
+    Output:        $output
+END
+}
+
+sub straight_line (@array) {
+    my %angles;
+    for my $i ( 0 .. $#array ) {
+        my $k = $array[$i];
+        for my $j ( $i + 1, $#array ) {
+            next unless $i != $j;
+            next unless defined $array[$j];
+            my $l  = $array[$j];
+            my $a1 = find_angle( $k, $l );
+            my $a2 = find_angle( $l, $k );
+            $angles{$a1} = 1;
+            $angles{$a2} = 1;
+        }
+    }
+    return scalar keys %angles <= 2 ? 'true' : 'false';
+}
+
+sub find_angle ( $p1, $p2 ) {
+    return 
+    # sprintf '%.06f', 
+        atan2( $p1->[1] - $p2->[1], $p1->[0] - $p2->[0] );
+}