Merge pull request #8801 from wlmb/challenges

Solve PWC237

3 files changed, 57 insertions, 0 deletions

diff --git a/challenge-237/wlmb/blog.txt b/challenge-237/wlmb/blog.txt
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+++ b/challenge-237/wlmb/blog.txt
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+https://wlmb.github.io/2023/10/01/PWC237/
diff --git a/challenge-237/wlmb/perl/ch-1.pl b/challenge-237/wlmb/perl/ch-1.pl
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+++ b/challenge-237/wlmb/perl/ch-1.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 237
+# Task 1:  Seize The Day
+#
+# See https://wlmb.github.io/2023/10/01/PWC237/#task-1-seize-the-day
+use v5.36;
+use experimental qw(for_list);
+use POSIX qw(floor);
+die <<~"FIN" unless @ARGV && @ARGV%4==0;
+    Usage: $0 Y1 M1 W1 D1 [Y2 M2 W2 D2...]
+    to find the number corresponding to day Dn of week (1=Monday),
+    weekday of month Wn, month Mn, year Yn
+    FIN
+my @days_of_month=([31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],    # length of months
+                      [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]);   # nonleap and leap
+my @days_to_month=([0,3,3,6,1,4,6,2,5,0,3,5], # days to start of month nonleap and leap mod7
+                      [0,3,4,0,2,5,0,3,6,1,4,6]);
+my @ordinal=qw(first second third fourth fifth);
+my @day_name=qw(Sunday Monday Tuesday Wednesday Thursday Friday Saturday);
+my @month_name=qw(January February March April May June
+                  July August September October November Dececmber);
+for my($year, $month, $weekday, $day_of_week) (@ARGV){
+    warn "Weekday should be between 1 and 5: $weekday", next unless 1<=$weekday<=5;
+    warn "Day of week should be between 1 (Mon) and 7 (Sun): $day_of_week", next
+        unless 1<=$day_of_week<=7;
+    warn "Month should be between 1 and 12", next unless 1<=$month<=12;
+    --$_ for $weekday, $month; # start at 0
+    $day_of_week%=7; # Sun is now 0
+    my $reduced_year=$year%400; # Cycle repeats after 400 years
+    my $previous_leaps=(floor(($reduced_year+3)/4)
+                        -floor(($reduced_year+3)/100))%7; # Leap years before start of given year
+    my $start=($reduced_year+$previous_leaps+6)%7; # starting day of week of year, counting from sunday==0
+    my $given_is_leap=($reduced_year==0 || ($reduced_year%100!=0 && $reduced_year%4==0))||0;
+    my $beggining=($days_to_month[$given_is_leap][$month]+$start)%7; # first day of week of month
+    my $day=1+($day_of_week-$beggining)%7+$weekday*7;            # desired date
+    $day=0 if $day>$days_of_month[$given_is_leap][$month];    # check it lies within month
+    say "The $ordinal[$weekday] $day_name[$day_of_week] of $month_name[$month] in $year is $day";
+}
diff --git a/challenge-237/wlmb/perl/ch-2.pl b/challenge-237/wlmb/perl/ch-2.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 237
+# Task 2:  Maximise Greatness
+#
+# See https://wlmb.github.io/2023/10/01/PWC237/#task-2-maximise-greatness
+use v5.36;
+die <<~"FIN" unless @ARGV;
+    Usage: $0 N1 [N2...]
+    to find the greatness of the array N1 N2...
+    FIN
+my @copy=my @sorted=sort {$a<=>$b} @ARGV;
+my $current=shift @sorted;
+my @permutation;
+while(@copy){
+    my $next=shift @copy;
+    push(@permutation, $next), $current=shift @sorted if $current<$next
+}
+say "@ARGV -> ", 0+@permutation;