ch-2.raku do-over

1 files changed, 25 insertions, 24 deletions

diff --git a/challenge-202/mark-anderson/raku/ch-2.raku b/challenge-202/mark-anderson/raku/ch-2.raku
index d29886a5f8..ef80125df6 100644
--- a/challenge-202/mark-anderson/raku/ch-2.raku
+++ b/challenge-202/mark-anderson/raku/ch-2.raku
@@ -1,33 +1,34 @@
 #!/usr/bin/env raku
+use Test;
 
-say widest-valley(< 1 2 2 5 4 1 0 2 3 2 1 3 4 3 1 32 11 11 8 >);
-say widest-valley(< 1 2 2 5 4 1 0 0 0 0 0 2 3 4 5 32 11 11 8 >);
-say widest-valley(< 1 1 1 1 1 2 5 >);
-say widest-valley(< 32 11 11 8 >);
-say widest-valley(< 11 11 11 8 4 2 4 8 11 11 11 >);
-say widest-valley((10..50).roll(1000));
+is-deeply widest-valley(1, 5, 5, 2, 8), 
+                       (5, 5, 2, 8),                  'Example 1';
+is-deeply widest-valley(2, 6, 8, 5),    
+                       (2, 6, 8),                     'Example 2';
+is-deeply widest-valley(9, 8, 13, 13, 2, 2, 15, 17),  
+                       (13, 13, 2, 2, 15, 17),        'Example 3';
+is-deeply widest-valley(1, 3, 3, 2, 1, 2, 3, 3, 2), 
+                       (3, 3, 2, 1, 2, 3, 3),         'Example 4';
+is-deeply widest-valley(2, 1, 2, 1, 3), 
+                       (2, 1, 2),                     'Example 5';
 
-sub widest-valley(*@a)
-{
-    my @decreasing;
-    my @increasing;
+say widest-valley((10..50).roll(100_000)); # takes ~ 3 seconds
 
-    until @a <= 1
-    {
-        my $k = ([\>=] @a).first({ .not }, :k) // @a.elems;
-        @decreasing.push: @a.splice(0, $k, @a[$k-1]);
-        
-        $k = ([\<=] @a).first({ .not }, :k) // @a.elems;
-        @increasing.push: @a.splice(0, $k, @a[$k-1]);
-    }
-
-    @a = @decreasing Z @increasing;
+# This is ugly but I was determined to use a regular expression 🙄  
+sub widest-valley(*@n)
+{
+    my %h = -1 => 'D', 0 => 'F', 1 => 'U'; 
+    my $s = @n.rotor(2 => -1).map({ %h{(.[1] - .[0]).sign } }).join;
+    my $h = 0;
 
-    my $a := gather for @a
+    my $r := gather for $s ~~ m:g/ U (F*) D / -> $m
     {
-        pop  .[0];
-        take .comb(/\d+/)
+        take ($h, $m.to.pred);
+        $h = $m.to.pred - ($m[0] // '').chars;
+        LAST { take ($h, $s.chars) }
     }
 
-    $a[$_] given $a.cache>>.elems.maxpairs.first.key
+    my $m := $r>>.minmax;
+    my $k  = $m>>.elems>>.flat.maxpairs.first.key;
+    @n[ $m[$k] ]
 }