Laugh

3 files changed, 124 insertions, 0 deletions

diff --git a/challenge-138/blog.txt b/challenge-138/blog.txt
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+++ b/challenge-138/blog.txt
@@ -0,0 +1 @@
+https://jacoby.github.io/2021/11/08/i-thank-you-for-the-days-the-weekly-challenge-138.html
diff --git a/challenge-138/dave-jacoby/perl/ch-1.pl b/challenge-138/dave-jacoby/perl/ch-1.pl
new file mode 100644
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+++ b/challenge-138/dave-jacoby/perl/ch-1.pl
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+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature qw{ say state postderef signatures };
+no warnings qw{ experimental };
+
+use DateTime;
+
+for my $y ( 2000 .. 2040 ) {
+    say join "\t", $y, workdays2($y), workdays1($y);
+}
+
+# The brute force solution, where I go through each year,
+# checking if each day is a work day, and keeping count. 
+
+sub workdays1 ( $year ) {
+    my $day = DateTime->new(
+        day       => 1,
+        month     => 1,
+        year      => $year,
+        time_zone => 'floating'
+    );
+    my $c = 0;
+    while ( $year == $day->year ) {
+        $c++ if $day->day_of_week <= 5;
+        $day->add( days => 1 );
+    }
+    return $c;
+}
+
+# But there are ONLY 14 years. Leap year or not = 2. Days of week = 7.
+# 2 * 7 == 14. So it's perfectly reasonable to know that, if the year
+# is a leapyar and starts on a Saturday, or starts on a Sunday, leap year
+# or no, that's going to be a 260-workday year, and if it's a leap year
+# and starts on Monday, Tuesday, Wednesday or Thurday, there will be
+# 262, and otherwise, there will be 261.
+
+sub workdays2( $year ) {
+    my $table = {};
+    $table->{0}{1} = 261;
+    $table->{0}{2} = 261;
+    $table->{0}{3} = 261;
+    $table->{0}{4} = 261;
+    $table->{0}{5} = 261;
+    $table->{0}{6} = 260;
+    $table->{0}{7} = 260;
+    $table->{1}{1} = 262;
+    $table->{1}{2} = 262;
+    $table->{1}{3} = 262;
+    $table->{1}{4} = 262;
+    $table->{1}{5} = 261;
+    $table->{1}{6} = 260;
+    $table->{1}{7} = 261;
+    my $day = DateTime->new(
+        day       => 1,
+        month     => 1,
+        year      => $year,
+        time_zone => 'floating'
+    );
+    return $table->{ $day->is_leap_year }{ $day->dow };
+}
+
diff --git a/challenge-138/dave-jacoby/perl/ch-2.pl b/challenge-138/dave-jacoby/perl/ch-2.pl
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+++ b/challenge-138/dave-jacoby/perl/ch-2.pl
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+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature qw{ say postderef signatures state };
+no warnings qw{ experimental };
+
+use List::Util qw{ sum0 uniq };
+
+my @squares = map { $_**2 } 1 .. 100;
+
+for my $n (@squares) {
+    my $split = split_number($n);
+    say join "\t", '', $split, $n,;
+}
+
+sub split_number($n) {
+    my $sqrt  = sqrt($n);
+    my @split = split //, $n;
+    if ( scalar @split == 1 ) {
+        my $s = shift @split;
+        return $s == $sqrt ? 1 : 0;
+    }
+    else {
+        my @numbers = break_up( 1, @split );
+        for my $num (@numbers) {
+            my $sum = sum0 split /\D/, $num;
+            return 1 if $sqrt == $sum;
+        }
+    }
+    return 0;
+}
+
+sub break_up ( $position, @array ) {
+    my @output;
+    my $len = scalar @array;
+    my @dup = @array;
+    if ( $len <= $position ) {
+        return join '+', @array;
+    }
+
+    my @copy;
+    my $i = 0;
+    while (@dup) {
+        if ( $i eq $position ) {
+            my $x = shift @dup;
+            $copy[-1] .= $x;
+        }
+        else {
+            push @copy, shift @dup;
+        }
+        $i++;
+    }
+
+    push @output, break_up( $position,     @copy );
+    push @output, break_up( $position + 1, @array );
+
+    @output = uniq sort grep { defined } @output;
+    return @output;
+}