better ways than brute force

2 files changed, 47 insertions, 46 deletions

diff --git a/challenge-043/markus-holzer/perl6/ch-2.p6 b/challenge-043/markus-holzer/perl6/ch-2.p6
index 11b4b2a19c..f3123b70ce 100644
--- a/challenge-043/markus-holzer/perl6/ch-2.p6
+++ b/challenge-043/markus-holzer/perl6/ch-2.p6
@@ -1,61 +1,33 @@
 use Test;
+use Math::SelfDescriptiveNumbers;
 
-# all self-descriptive numbers 
-# - must be at least base digits long
-# - have digit sums equal to their base, 
-# - are multiples of that base 
-# - each digit d at position n counts how many instances of digit n are in m
-
-multi sub MAIN( Int $base where $_ < 37 )
+multi sub MAIN()
 {
-    .base( $base ).say for 
-        self-descriptive-candidates( $base )
-        .grep({ is-self-descriptive( $_, $base ) });
+    for self-descriptive-numbers() -> ($base, $numbers)
+    {
+        say output( $base, $numbers );
+    }
 }
 
+multi sub MAIN( Int $base where 1 < $base < 37 )
+{
+    say output( $base, self-descriptive-numbers-of( $base ) );
+}
 
 multi sub MAIN( "test" ) 
 {
-    ok base-start( 2 )  == 2;
-    ok base-start( 10 ) == 1000000000;
-    ok base-start( 16 ) == 0x1000000000000000;
-
     # test values from Wikipedia
-    ok is-self-descriptive( parse-base('21200',5), 5 );
+    ok is-self-descriptive( :number(parse-base('21200',5)), :base(5) );
+    ok is-self-descriptive( :number('21200'), :base(5) );
+    ok is-self-descriptive( 'C210000000001000', 16 );
     ok is-self-descriptive( 0xC210000000001000, 16 );
-    ok is-self-descriptive( 6210001000, 10 );
     ok !is-self-descriptive( 3210001000, 10 );
-    ok self-descriptive-candidates(4).first({ is-self-descriptive( $_, 4) }).base(4) eq "1210";
-    ok self-descriptive-candidates(5).first({ is-self-descriptive($_, 5) }).base(5) eq "21200";
-    ok self-descriptive-candidates(7).first({ is-self-descriptive($_, 7) }).base(7) eq "3211000";
-}
-
-
-sub is-self-descriptive( $number, $base ) 
-{
-    state @digits = (0 .. 9).Array.append( ('A' .. 'Z').Array );
-    
-    my $base-str = $number.base( $base );
-
-    !so $base-str.comb.pairs.first( -> $p
-    {
-        my $digit = @digits[ $p.key ];
-        my $count-is = ( $base-str ~~ m:g/ ($digit) / ).elems;
-        $count-is != parse-base( $p.value.Str, $base );
-    });
-}
-
-
-sub self-descriptive-candidates( $base )
-{
-    my $base-start = base-start($base);
-    return $base-start, $base-start + $base, { $_ + $base } ...^ $base-start * $base;
 }
 
-sub base-start( $base )
+sub output( $base, $numbers )
 {
-    my $zeroes = $base - 1;
-    my $n = "1" ~ ( "0" x $zeroes );
-    parse-base( $n, $base );
-}
+    my $num-base = $numbers.map( *.base( $base ) ).join(',');
+    my $num-dec  = $numbers.join(',');
 
+    "Base $base, " ~ ( $numbers.elems ?? "$num-base; $num-dec (decimal)" !! '---' );
+}
\ No newline at end of file
diff --git a/challenge-043/markus-holzer/perl6/lib/Math/SelfDescriptiveNumbers.pm6 b/challenge-043/markus-holzer/perl6/lib/Math/SelfDescriptiveNumbers.pm6
new file mode 100644
index 0000000000..8409826549
--- /dev/null
+++ b/challenge-043/markus-holzer/perl6/lib/Math/SelfDescriptiveNumbers.pm6
@@ -0,0 +1,29 @@
+unit module Math::SelfDescriptiveNumbers;
+
+multi sub is-self-descriptive( Int $number, Int $base ) is export {
+    is-self-descriptive( :$number, :$base );
+}
+
+multi sub is-self-descriptive( Int :$number, Int :$base ) is export {
+    $number ∈ self-descriptive-numbers-of( $base );
+}
+
+multi sub is-self-descriptive( Str $number, Int $base ) is export {
+    is-self-descriptive( :$number, :$base );
+}
+
+multi sub is-self-descriptive( Str :$number, Int :$base ) is export {
+    parse-base( $number, $base ) ∈ self-descriptive-numbers-of( $base );
+}
+
+sub self-descriptive-numbers is export {
+    ( 1 .. 36 ).map({ ( $_, self-descriptive-numbers-of( $_ ) ) });
+}
+
+multi sub self-descriptive-numbers-of( Int $base where $_ ~~ 1|2|3|6 ) is export { () }
+multi sub self-descriptive-numbers-of( Int $base where $_ == 4 ) is export { (100, 136) }
+multi sub self-descriptive-numbers-of( Int $base where $_ == 5 ) is export { (1425) }
+multi sub self-descriptive-numbers-of( Int $base ) is export { 
+    ( parse-base( ($base - 4).base( $base ) ~  "21" ~ ( '0' x ($base - 7) ) ~ '1000', $base ) )
+}
+