rjt's Week 048 solutions and blogs

Author: rjt-pl

challenge-048/ryan-thompson/README.md

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 # Ryan Thompson
 
-## Week 047 Solutions
+## Week 048 Solutions
 
-### Task 1 › Roman Calculator
+### Task 1 › Survivor
 
  * [Perl](perl/ch-1.pl)
- * **Raku:** No Raku solution this week, sorry.
+ * [Raku](raku/ch-1.p6)
 
-### Task 2 › Gapful Numbers
+### Task 2 › Palindrome Dates
 
  * [Perl](perl/ch-2.pl)
  * [Raku](raku/ch-2.p6)
 
 ## Blogs
 
- * [Task 1 › Roman Calculator](http://www.ry.ca/2020/02/roman-calculator/)
- * [Task 2 › Gapful Numbers](http://www.ry.ca/2020/02/gapful-numbers/)
+ * [Task 1 › Survivor](http://www.ry.ca/2020/02/survivor-josepheus-problem/)
+ * [Task 2 › Palindrome Dates](http://www.ry.ca/2020/02/palindrome-dates/)

challenge-048/ryan-thompson/blog.txt

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+http://www.ry.ca/2020/02/survivor-josepheus-problem/

challenge-048/ryan-thompson/blog1.txt

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+http://www.ry.ca/2020/02/palindrome-dates/

challenge-048/ryan-thompson/perl/ch-1.pl

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+#!/usr/bin/env perl
+#
+# ch-1.pl - Survivor
+#
+# Ryan Thompson <[email protected]>
+
+use 5.010;
+use warnings;
+use strict;
+
+say survivor(shift) and exit if @ARGV;
+
+# Linked list solution
+sub survivor {
+    my $N = shift;
+    my @ll = (undef, 2..$N, 1); # Circular linked list
+    my $cur = 1;
+    $ll[$cur] = $ll[$ll[$cur]], $cur = $ll[$cur] until $ll[$cur] == $cur;
+
+    $cur;
+}
+
+sub analytic {
+    my $N = shift;
+    2 * ($N - 2**int( log($N) / log(2) )) + 1;
+}
+
+#
+# Benchmarking and Tests
+#
+
+use Benchmark qw/cmpthese/;
+use Test::More;
+
+cmpthese(-5, {
+    linked      => sub { survivor($_) for 1..100 },
+    analytic    => sub { analytic($_) for 1..100 },
+});
+
+is survivor(100), 73;
+is survivor(50), 37;
+is survivor($_), analytic($_) for 1..100;
+done_testing;

challenge-048/ryan-thompson/perl/ch-2.pl

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+#!/usr/bin/env perl
+#
+# ch-2.pl - Palindrome Dates (mm/dd/yyyy)
+#
+# Ryan Thompson <[email protected]>
+
+use warnings;
+use strict;
+
+# All of the 2-digit years must also be months
+my @yy = sort map { chop . ($_||0) } 1..12;
+
+# Ensure printing in the correct order, with minimal looping
+for my $dd (qw<02 12 22>) {
+    for my $yy (@yy) {
+        printf "%02d-%02d-%02d%02d\n",
+            scalar reverse($yy), $dd, scalar reverse($dd), $yy;
+    }
+}

challenge-048/ryan-thompson/raku/ch-1.p6

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+#!/usr/bin/env perl6
+
+# ch-1.p6 - Survivor
+#
+# Ryan Thompson <[email protected]>
+
+sub MAIN( Int $N = 50 ) {
+    my Int @ll = 0, |[1..$N].rotate;
+    my Int $cur = 1;
+
+    @ll[$cur] = @ll[ @ll[$cur] ] and $cur = @ll[$cur] until @ll[$cur] == $cur;
+
+    say $cur;
+}

challenge-048/ryan-thompson/raku/ch-2.p6

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+#!/usr/bin/env perl6
+
+# ch-2.p6 - Palindrome Dates (mm/dd/yyyy)
+#
+# Ryan Thompson <[email protected]>
+
+for (<02 12 22> X (1..12)».fmt('%02d')».flip.sort).flat -> $dd, $yy {
+    say "{$yy.flip}-$dd-{$dd.flip}$yy";
+}
+
+# Naive method
+#.say for (2000..2999).map({ $_.flip.comb(2), $_ }).flat.grep: &valid-date;
+
+#| Return True if a mmddyyyy date is valid
+#  This won't work in general; it works here because of the range (see blog)
+#sub valid-date( $m, $d, $y ) {  1 ≤ $m ≤ 12 and 1 ≤ $d ≤ 31; }