Add solution to challenge 107

5 files changed, 114 insertions, 0 deletions

diff --git a/challenge-107/wlmb/blog.txt b/challenge-107/wlmb/blog.txt
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+++ b/challenge-107/wlmb/blog.txt
@@ -0,0 +1 @@
+https://wlmb.github.io/2021/04/05/PWC107/
diff --git a/challenge-107/wlmb/perl/Calc.pm b/challenge-107/wlmb/perl/Calc.pm
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+++ b/challenge-107/wlmb/perl/Calc.pm
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+package Calc;
+
+use strict;
+use warnings;
+
+sub new { bless {}, shift; }
+sub add { }
+sub mul { }
+sub div { }
+our $scalar;
+our @array;
+our %hash;
+
+1;
diff --git a/challenge-107/wlmb/perl/ch-1.pl b/challenge-107/wlmb/perl/ch-1.pl
new file mode 100755
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+++ b/challenge-107/wlmb/perl/ch-1.pl
@@ -0,0 +1,53 @@
+#!/usr/bin/env perl
+# Perl weekly challenge 107
+# Task 1: Self-descriptive Numbers
+# Use some properties to accelerate their generation
+# Use letter to go beyond base 10
+#
+# See https://wlmb.github.io/2021/04/05/PWC107/#task-1-self-descriptive-numbers
+use strict;
+use warnings;
+use v5.12;
+use List::Util qw(all);
+
+die 'Use: ./ch1.pl howmany' unless @ARGV;
+my $howmany=shift @ARGV;
+exit unless $howmany > 0;
+my @results;
+my $largest_base=36; #allows ten decimal digits and 26 letters
+my @letter_from_digit=(0..9,'a'..'z');
+my $base=2;
+
+ RESULT:
+    while($howmany>@results){
+	++$base;
+	last RESULT if $base>$largest_base;
+	for my $firstdigit(1..$base-1){
+	    try([$firstdigit],0,$base, $firstdigit);
+	    last RESULT if @results==$howmany;
+	}
+}
+my $n=1;
+foreach(@results){
+    say sprintf("%2d- Base %2d:  %s", $n++, scalar @$_,
+                join('', map {$letter_from_digit[$_]} @$_));
+}
+sub try {
+    my ($current,$position,$base, $sum)=@_;
+    if($position==$base-1){
+	push @results, $current if check($current);
+	return;
+    }
+    for my $digit(0..$base-$sum){
+	try([(@$current,$digit)], $position+1, $base, $sum+$digit);
+    }
+}
+
+sub check {
+    my $number=shift;
+    my @digits=@$number;
+    my @need=(0)x@digits;
+    my @have=(0)x@digits;
+    map {$need[$_]=$digits[$_]; $have[$digits[$_]]++} 0..@digits-1;
+    return all {$need[$_]==$have[$_]} 0..@digits-1;
+}
diff --git a/challenge-107/wlmb/perl/ch-1a.pl b/challenge-107/wlmb/perl/ch-1a.pl
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+++ b/challenge-107/wlmb/perl/ch-1a.pl
@@ -0,0 +1,28 @@
+#!/usr/bin/env perl
+# Perl weekly challenge 107
+# Task 1: Self-descriptive Numbers
+# Brute force solution.
+#
+# See https://wlmb.github.io/2021/04/05/PWC107/#task-1-self-descriptive-numbers
+use strict;
+use warnings;
+use v5.12;
+use List::Util qw(all);
+die 'Use: ./ch1a.pl howmany' unless @ARGV;
+my $howmany=shift @ARGV;
+for my $n(0..10**10-1){ # number of digits <=10
+    if(check($n)){
+	say $n;
+	--$howmany;
+	last if $howmany<=0;
+    }
+}
+
+sub check {
+    my $number=shift;
+    my @digits=split '',$number;
+    my @need=(0)x@digits;
+    my @have=(0)x@digits;
+    map {$need[$_]=$digits[$_]; $have[$digits[$_]]++} 0..@digits-1;
+    return all {$need[$_]==$have[$_]} 0..@digits-1;
+}
diff --git a/challenge-107/wlmb/perl/ch-2.pl b/challenge-107/wlmb/perl/ch-2.pl
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+++ b/challenge-107/wlmb/perl/ch-2.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 107
+# Task 2: List Methods
+#
+# See https://wlmb.github.io/2021/04/05/PWC107/#task-2-list-methods
+use strict;
+use warnings;
+use v5.12;
+
+no strict "refs"; # don't be that strict
+die 'Use: ./ch-2.pl package [other package] [...]' unless @ARGV;
+foreach my $package(@ARGV){
+    eval "require $package";
+    die $@ if $@;
+    foreach my $key(sort keys %{"${package}::"}){
+	say $key if defined &{"${package}::$key"};
+    }
+}