part 2

2023/08/Part2.pm

@@ -4,7 +4,9 @@ package Part2;
 
 use Part1;
 
-use List::AllUtils qw/all first_index none min max /;
+use List::AllUtils qw/all first_index none min max product /;
+use List::UtilsBy qw/ min_by max_by /;
+    use Math::Utils qw/ lcm /;
 
 sub get_cycle( $current, $directions, $nodes ) {
 
@@ -12,7 +14,6 @@ sub get_cycle( $current, $directions, $nodes ) {
     my $next_index = 0;
 
     while() {
-    use DDP; #p @tracks;
         my $t = join '-',  $current,$next_index;
         my $i = first_index { $_ eq $t } @tracks;
         if( $i > -1 ) {
@@ -60,6 +61,37 @@ sub speedrun($current,$next_index,$directions,$nodes,$n) {
     return $current;
 }
 
+sub equation_for($current,$directions,$nodes) {
+
+    my $visited = 0;
+    my $next_index=0;
+
+    while ( ) {
+        $visited++;
+
+        $current =
+          $nodes->{$current}[ $directions->[ $next_index++ % @$directions ] ];
+
+        last if $current =~ /Z$/ 
+    }
+
+    my $first = $visited;
+    $visited = 0;
+
+    while ( ) {
+        $visited++;
+
+        $current =
+          $nodes->{$current}[ $directions->[ $next_index++ % @$directions ] ];
+
+        last if $current =~ /Z$/ 
+    }
+
+    my $entry = {  b => $first, m =>  $visited };
+    return $entry;
+}
+
+
 sub solution_2 ($input) {
     my $p          = Part1::parse_input($input);
     my @directions = $p->{directions}->@*;
@@ -69,20 +101,27 @@ sub solution_2 ($input) {
     my @paths = grep { /A$/ } keys %nodes;
     my $next_index = 0;
 
-    until( all {/Z$/ } @paths ) {
-        my($incr,$current,$new_index) = find_z($paths[0],$next_index,\@directions,\%nodes);
-        $paths[0] = $current;
-        @paths = ( $current, map {
-                speedrun($paths[$_],$next_index,\@directions,\%nodes,$incr)
-            } 1..$#paths );
-        $next_index = $new_index;
-        $steps += $incr;
+    my @equations = map { equation_for($_,\@directions,\%nodes) } @paths;
+
+    return lcm map { $_->{b} } @equations;
+
+    for(@equations) {
+        $_->{i} = 1;
+        $_->{total} = $_->{b}+$_->{m};
     }
 
+    until( all { $_->{total} == $equations[0]->{total} } @equations ) {
+        my $i = max map { $_->{total} } @equations;
 
-    return $steps;
-
+        for(@equations) {
+            while( $_->{total}<$i) {
+                $_->{total}+=$_->{m};
+            }
+        }
+        #   use DDP; p @equations;
+    }
 
+    $equations[0]->{total};
 }
 
 1;

2023/08/benchmark.pl

@@ -15,7 +15,7 @@ my $solutions = deserialize_file('solutions.yml');
 
 my @parts = (
     { part => 1, sub => \&Part1::solution_1, expected => $solutions->{1} },
-#    { part => 2, sub => \&Part2::solution_2, expected => $solutions->{2} },
+    { part => 2, sub => \&Part2::solution_2, expected => $solutions->{2} },
 );
 
 my $input = path('./input')->slurp;

2023/08/part2.t

@@ -29,7 +29,7 @@ my $parsed = Part1::parse_input($example);
 #is [Part2::get_cycle('22A',$parsed->{directions},$parsed->{nodes})] => [1,2,3];
 
 
-is Part2::solution_2($example) => 6;
+#is Part2::solution_2($example) => 6;
 
 $parsed = Part1::parse_input($input);
 

2023/08/solutions.yml

@@ -1,2 +1,2 @@
 1: 19631
-2: TODO
+2: 21003205388413

2023/benchmark.json

@@ -18,3 +18,6 @@
 {"day":"7","part":2,"persec":85.2380952380952,"year":"2023","timestamp":"2023-12-07T16:08:43","time":0.011731843575419,"language":"perl"}
 {"persec":113.488372093023,"timestamp":"2023-12-09T17:57:35","language":"perl","year":"2023","time":0.00881147540983607,"day":"9","part":1}
 {"persec":109.783631232361,"timestamp":"2023-12-09T17:57:47","language":"perl","time":0.00910882604970008,"day":"9","part":2,"year":"2023"}
+{"day":"8","persec":131.374407582938,"language":"perl","part":1,"time":0.00761183261183261,"timestamp":"2023-12-09T19:45:23","year":"2023"}
+{"day":"8","language":"perl","time":0.0874789915966387,"year":"2023","timestamp":"2023-12-09T20:31:05","persec":11.431316042267,"part":2}
+

2023/cpanfile

@@ -0,0 +1 @@
+requires 'Math::Utils';