Merge pull request #355 from Firedrake/rogerbw-016

Roger's solution. I hate everything to do with Bitcoin.

2 files changed, 55 insertions, 0 deletions

diff --git a/challenge-016/roger-bell-west/perl5/ch-1.pl b/challenge-016/roger-bell-west/perl5/ch-1.pl
new file mode 100755
index 0000000000..685d34d982
--- /dev/null
+++ b/challenge-016/roger-bell-west/perl5/ch-1.pl
@@ -0,0 +1,23 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+
+use Math::BigFloat;
+
+my $n=$ARGV[0] || 100;
+
+my $remaining=Math::BigFloat->new(1);
+my $max=0;
+my $maxp=0;
+
+foreach my $participant (1..$n) {
+  my $portion=$remaining*$participant/$n;
+  if ($portion > $max) {
+    $max=$portion;
+    $maxp=$participant;
+  }
+  $remaining-=$portion;
+}
+
+print "$maxp: $max\n";
diff --git a/challenge-016/roger-bell-west/perl5/ch-2.pl b/challenge-016/roger-bell-west/perl5/ch-2.pl
new file mode 100755
index 0000000000..710c38c6fe
--- /dev/null
+++ b/challenge-016/roger-bell-west/perl5/ch-2.pl
@@ -0,0 +1,32 @@
+#! /usr/bin/perl
+
+use strict;
+use warnings;
+
+use Encode::Base58::GMP;
+use Math::GMPz qw(:mpz);
+use Digest::SHA qw(sha256 sha256_hex);
+
+foreach my $address (@ARGV) {
+  unless ($address =~ /^[1-9A-HJ-NP-Za-km-z]*$/) {
+    warn "$address\ninvalid characters\n";
+    next;
+  }
+  my $a=decode_base58($address,'bitcoin');
+  my $ah=Rmpz_get_str($a,16);
+  if (length($ah)%2==1) {
+    $ah='0'.$ah;
+  }
+  my @e=($ah =~ /(..)/g);
+  while (scalar @e < 25) {
+    unshift @e,'00';
+  }
+  my $cksum=join('',splice(@e,-4));
+  my $raw=pack('C*',map {hex($_)} @e);
+  my $digest=substr(sha256_hex(sha256($raw)),0,8);
+  if ($digest eq $cksum) {
+    print join('',@e),"\n";
+  } else {
+    warn "$address\nCalculated $digest does not match stored $cksum\n";
+  }
+}