Data commit

Task/Pancake-numbers/Perl/pancake-numbers.pl

@@ -0,0 +1,43 @@
+use strict;
+use warnings;
+use feature 'say';
+
+sub pancake {
+    my($n) = @_;
+    my ($gap, $sum, $adj) = (2, 2, -1);
+    while ($sum < $n) { $sum += $gap = $gap * 2 - 1 and $adj++ }
+    $n + $adj;
+}
+
+my $out;
+$out .= sprintf "p(%2d) = %2d ", $_, pancake $_ for 1..20;
+say $out =~ s/.{1,55}\K /\n/gr;
+
+# Maximum number of flips plus examples using exhaustive search
+sub pancake2 {
+    my ($n) = @_;
+    my $numStacks = 1;
+    my @goalStack = 1 .. $n;
+    my %newStacks = my %stacks = (join(' ',@goalStack), 0);
+    for my $k (1..1000) {
+        my %nextStacks;
+        for my $pos (2..$n) {
+            for my $key (keys %newStacks) {
+                my @arr = split ' ', $key;
+                my $cakes = join ' ', (reverse @arr[0..$pos-1]), @arr[$pos..$#arr];
+                $nextStacks{$cakes} = $k unless $stacks{$cakes};
+            }
+        }
+        %stacks = (%stacks, (%newStacks = %nextStacks));
+        my $perms    = scalar %stacks;
+        my %inverted = reverse %stacks;
+        return $k-1, $inverted{(sort keys %inverted)[-1]} if $perms == $numStacks;
+        $numStacks = $perms;
+   }
+}
+
+say "\nThe maximum number of flips to sort a given number of elements is:";
+for my $n (1..9) {
+    my ($a,$b) = pancake2($n);
+    say "pancake($n) = $a example: $b";
+}