From b59f8f4008bb8ec491a9e89f097f04ce54aed4c0 Mon Sep 17 00:00:00 2001
From: Dave Jacoby <jacoby.david@gmail.com>
Date: Mon, 5 Jul 2021 17:42:23 -0400
Subject: My Work Here Is Done...

---
 challenge-120/dave-jacoby/blog.txt     |  1 +
 challenge-120/dave-jacoby/perl/ch-1.pl | 18 +++++++++++++
 challenge-120/dave-jacoby/perl/ch-2.pl | 48 ++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+)
 create mode 100644 challenge-120/dave-jacoby/blog.txt
 create mode 100644 challenge-120/dave-jacoby/perl/ch-1.pl
 create mode 100644 challenge-120/dave-jacoby/perl/ch-2.pl

diff --git a/challenge-120/dave-jacoby/blog.txt b/challenge-120/dave-jacoby/blog.txt
new file mode 100644
index 0000000000..0f29f7f2da
--- /dev/null
+++ b/challenge-120/dave-jacoby/blog.txt
@@ -0,0 +1 @@
+https://jacoby.github.io/2021/07/05/its-about-time-weekly-challenge-120.html
diff --git a/challenge-120/dave-jacoby/perl/ch-1.pl b/challenge-120/dave-jacoby/perl/ch-1.pl
new file mode 100644
index 0000000000..8e21ea4327
--- /dev/null
+++ b/challenge-120/dave-jacoby/perl/ch-1.pl
@@ -0,0 +1,18 @@
+#!/usr/bin/env perl
+
+use feature qw{say state signatures};
+use strict;
+use warnings;
+use utf8;
+no warnings qw{ experimental };
+
+for my $n ( 18, 101 ) {
+    say join "\t", '', $n, swap_bits($n);
+}
+
+sub swap_bits ($n) {
+    my $b = sprintf '%08b', $n;
+    my $r = join '', map { scalar reverse($_) } ( $b =~ /../g );
+    my $s = oct( '0b' . $r );
+    return $s;
+}
diff --git a/challenge-120/dave-jacoby/perl/ch-2.pl b/challenge-120/dave-jacoby/perl/ch-2.pl
new file mode 100644
index 0000000000..43b342f01c
--- /dev/null
+++ b/challenge-120/dave-jacoby/perl/ch-2.pl
@@ -0,0 +1,48 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature qw{ postderef say signatures state };
+no warnings qw{ experimental };
+
+my @times = qw{ 3:10 4:00 4:20 6:00 11:59 12:00 3:21 };
+@times = map { "11:$_" } 20 .. 65;
+
+for my $time (@times) {
+    $time = fix_time($time);
+    my $angle = clock_angle($time);
+    say join "\t", '', $time, $angle;
+}
+
+sub fix_time ($time) {
+    my ( $hour, $minute ) = split /:/, $time;
+    $hour += 1 if $minute >= 60;
+    $minute = sprintf '%02d', $minute % 60;
+    $hour   = $hour % 12;
+    $hour   = $hour ? $hour : 12;
+    return join ':', $hour, $minute;
+}
+
+sub clock_angle ($time) {
+    my ( $hour, $minute ) = split /:/, $time;
+    my $minute_angle = minute_angle($minute);
+    my $hour_angle   = hour_angle( $hour, $minute );
+    my ( $min, $max ) = sort $minute_angle, $hour_angle;
+    my $angle = $max - $min;
+    if ( $angle > 180 ) {
+        $angle = abs $min - $max;
+    }
+    if ( $angle > 180 ) {
+        $angle = 360 - $angle;
+    }
+    return $angle;
+}
+
+sub hour_angle ( $hour, $minute ) {
+    $hour++ if $minute > 60;
+    return ( ( $hour % 12 ) * 30 ) + ( ( $minute % 60 ) / 2 );
+}
+
+sub minute_angle ($minute) {
+    return 6 * ( $minute % 60 );
+}
-- 
cgit