- Added solutions by Laurent Rosenfeld.

5 files changed, 94 insertions, 0 deletions

diff --git a/challenge-107/laurent-rosenfeld/blog.txt b/challenge-107/laurent-rosenfeld/blog.txt
new file mode 100644
index 0000000000..a92a0befe6
--- /dev/null
+++ b/challenge-107/laurent-rosenfeld/blog.txt
@@ -0,0 +1 @@
+http://blogs.perl.org/users/laurent_r/2021/04/perl-weekly-challenge-107-self-descripting-numbers-and-list-methods.html
diff --git a/challenge-107/laurent-rosenfeld/perl/ch-1.pl b/challenge-107/laurent-rosenfeld/perl/ch-1.pl
new file mode 100644
index 0000000000..054e4f5d18
--- /dev/null
+++ b/challenge-107/laurent-rosenfeld/perl/ch-1.pl
@@ -0,0 +1,47 @@
+use strict;
+use warnings;
+use feature qw /say/;
+use constant DIGITS => ('0'..'9', 'A'..'Z');
+use constant MAX => 3;
+my $count = 0;
+
+sub to_base_b { # Converts decimal number to base b string
+    my($dec, $base) = @_;
+    my @digits;
+    while ($dec) {
+        unshift @digits, (DIGITS)[$dec % $base];
+        $dec = int($dec/$base);
+    }
+    return join "", @digits;
+}
+
+sub check_self_desc {
+    my $base = shift;
+    for my $num ($base ** ($base -1) .. $base ** $base -1) {
+        my $num_in_b = to_base_b ($num, $base);
+        next unless $num_in_b =~ /0$/;
+        my @digits = split //, $num_in_b;
+        my $sum = 0;
+        $sum += $_ for split //, $num_in_b;
+        next if $sum != $base;
+        my $success = 1;
+        for my $rank (0..$base - 1) {
+            my $nb_digits = $digits[$rank];
+            my $num_occ = $num_in_b =~ s/$rank/$rank/g;
+            if ($num_occ != $nb_digits) {
+                $success = 0;
+                last;
+            }
+        }
+        if ($success) {
+            say "Number in base $base: $num_in_b; decimal: $num" ;
+            $count++;
+            return if $count >= MAX;
+        }
+    }
+}
+
+for my $base (2..10) {
+    check_self_desc($base);
+    last if $count >= MAX;
+}
diff --git a/challenge-107/laurent-rosenfeld/perl/ch-2.pl b/challenge-107/laurent-rosenfeld/perl/ch-2.pl
new file mode 100644
index 0000000000..5f5098ed06
--- /dev/null
+++ b/challenge-107/laurent-rosenfeld/perl/ch-2.pl
@@ -0,0 +1,7 @@
+use strict;
+use warnings;
+use feature qw /say/;
+
+while (<>) {
+    say $1 if /^\s*sub\s+(\w+)/;
+}
diff --git a/challenge-107/laurent-rosenfeld/raku/ch-1.raku b/challenge-107/laurent-rosenfeld/raku/ch-1.raku
new file mode 100644
index 0000000000..b25167da72
--- /dev/null
+++ b/challenge-107/laurent-rosenfeld/raku/ch-1.raku
@@ -0,0 +1,32 @@
+use v6;
+constant MAX = 4;
+
+my $*count = 0;
+for 2..Inf -> $base {
+    check-self-desc($base);
+    last if $*count >= MAX;
+}
+
+sub check-self-desc (Int $base) {
+    my $found = False;
+    for $base ** ($base -1) .. $base ** $base -1 -> $num {
+        my $num-in-b = $num.base($base);
+        next unless $num-in-b ~~ /0$/;
+        my @digits = $num-in-b.comb;
+        next if $base != [+] @digits;
+        my $success = True;
+        for 0..$base - 1 -> $rank {
+            if (+ $num-in-b.indices($rank) != @digits[$rank]) {
+                $success = False;
+                last;
+            }
+        }
+        if $success {
+            say "Number in base $base: $num-in-b; decimal: $num";
+            $*count++;
+            $found = True;
+            return if $*count >= MAX;
+        }
+    }
+    say "No self-descriptive number for base $base" unless $found;
+}
diff --git a/challenge-107/laurent-rosenfeld/raku/ch-2.raku b/challenge-107/laurent-rosenfeld/raku/ch-2.raku
new file mode 100644
index 0000000000..44ca49644d
--- /dev/null
+++ b/challenge-107/laurent-rosenfeld/raku/ch-2.raku
@@ -0,0 +1,7 @@
+use v6;
+
+sub MAIN (Str $file-name) {
+     for $file-name.IO.lines -> $line {
+        say ~$0 if $line ~~ /^\s* method \s+ (<[-'\w]>+)/;
+    }
+}