day06

06/1.pl

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+use 5.20.0;
+use experimental 'postderef';
+
+#use List::SomeUtils qw/ min_by /;
+use List::UtilsBy qw/ max_by/;
+
+my @stacks = split ' ', <>;
+
+my %seen;
+
+until( $seen{ join ':', @stacks }++ ) {
+    warn "@stacks\n";
+    my $col = max_by { $stacks[$_] }  0..$#stacks;
+    my $v = $stacks[$col];
+    $stacks[$col] = 0;
+    $stacks[ ++$col % @stacks ]++ while $v--;
+}
+
+say scalar keys %seen;
+

06/2.pl

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+use 5.20.0;
+use experimental 'postderef';
+
+use List::UtilsBy qw/ max_by/;
+
+my @stacks = split ' ', <>;
+
+my %seen;
+
+until( $seen{ join ':', @stacks }++ ) {
+    redistribute();
+}
+
+my $target = join ":", @stacks;
+
+my $i = 0;
+
+redistribute($i++) until $i and $target eq join ':', @stacks;
+
+say $i;
+
+sub redistribute {
+    warn "@stacks\n";
+    my $col = max_by { $stacks[$_] }  0..$#stacks;
+    my $v = $stacks[$col];
+    $stacks[$col] = 0;
+    $stacks[ ++$col % @stacks ]++ while $v--;
+}
+

06/example

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+0 2 7 0

06/input.txt

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+5	1	10	0	1	7	13	14	3	12	8	10	7	12	0	6