Merge pull request #388 from myrrhlin/pyrrhlin-pwc

Pyrrhlin pwc

5 files changed, 130 insertions, 0 deletions

diff --git a/challenge-015/michael-hamlin/README b/challenge-015/michael-hamlin/README
index 4314e219f4..c5737036e7 100644
--- a/challenge-015/michael-hamlin/README
+++ b/challenge-015/michael-hamlin/README
@@ -1 +1,7 @@
 Solutions by Michael Hamlin.
+
+
+Notes:
+
+* the Vigenere encoder/decoder supports multiple keys
+* don't forget that modular operator `%` does not do what you want with negative integers!
diff --git a/challenge-017/michael-hamlin/README b/challenge-017/michael-hamlin/README
index 4314e219f4..3c1a735306 100644
--- a/challenge-017/michael-hamlin/README
+++ b/challenge-017/michael-hamlin/README
@@ -1 +1,5 @@
 Solutions by Michael Hamlin.
+
+ch-1.pl  the Ackermann function grows so rapidly that I dont think I can
+test the real hyperness of my code, even with GMP.
+
diff --git a/challenge-017/michael-hamlin/perl5/ch-1.pl b/challenge-017/michael-hamlin/perl5/ch-1.pl
new file mode 120000
index 0000000000..bc89ccf6fc
--- /dev/null
+++ b/challenge-017/michael-hamlin/perl5/ch-1.pl
@@ -0,0 +1 @@
+t1-ackermann-two.pl
\ No newline at end of file
diff --git a/challenge-017/michael-hamlin/perl5/t1-ackermann-simple.pl b/challenge-017/michael-hamlin/perl5/t1-ackermann-simple.pl
new file mode 100644
index 0000000000..406fe6073e
--- /dev/null
+++ b/challenge-017/michael-hamlin/perl5/t1-ackermann-simple.pl
@@ -0,0 +1,35 @@
+#! /usr/bin/env perl
+#
+
+use 5.22.0;
+use warnings;
+use feature 'signatures';
+no warnings 'experimental::signatures';
+use integer;
+
+# really need the big integers when $m >= 4
+# use bigint lib => 'GMP';
+
+no warnings 'recursion';
+
+my $count = 0;
+
+sub _ack( $m, $n ) {
+    state @known;
+    $count++;
+    return $known[$m][$n] ||= do {
+        !$m ? $n + 1 :
+        !$n ? _ack($m - 1, 1) :
+        _ack($m - 1, _ack($m, $n - 1));
+    };
+}
+sub ack ( $m, $n ) {
+    die "the function is not defined for negative parameters" if $m < 0 || $n < 0;
+    return _ack($m, $n);
+}
+
+die "must give two nonnegative integers as input" unless @ARGV > 1;
+
+$" = ', ';
+say "A( @ARGV ) = ", ack(@ARGV), "  ...after $count calls.";
+
diff --git a/challenge-017/michael-hamlin/perl5/t1-ackermann-two.pl b/challenge-017/michael-hamlin/perl5/t1-ackermann-two.pl
new file mode 100644
index 0000000000..bdb6ce5e2a
--- /dev/null
+++ b/challenge-017/michael-hamlin/perl5/t1-ackermann-two.pl
@@ -0,0 +1,84 @@
+#! /usr/bin/env perl
+#
+
+use 5.22.0;
+use warnings;
+use feature 'signatures';
+no warnings 'experimental::signatures';
+
+# really need the big integers when $m >= 4
+# unfortunately the function grows so quickly even this doesnt help a lot
+use bigint lib => 'GMP';
+
+my $trace = 0;
+my %limits = (
+    5 => 0,
+    4 => 2,
+);
+
+# the hyper function, H_$n($a, $b), with $a = 2:
+sub _twohyper( $n, $b ) {
+    my $result = 2;
+    if ($n == 0) {
+        $result = $b + 1;
+    } elsif ($b == 0) {
+        # shortcut this?  but never happens in our problem
+        $result = $n == 1 ? 2 :
+            $n == 2 ? 0 : 1;
+    } elsif ($n == 1) {
+        $result += $b;
+    } elsif ($n == 2) {
+        $result *= $b;
+    } elsif ($b == 0) {
+        $result = 1;
+    } elsif ($b == 1) {
+        # result is just 2
+    } elsif ($n == 3) {
+        # exponentiation is iterated multiplication
+        $result = 1 << $b;  # 2 ** $b
+    } elsif ($n == 4) {
+        # tetration is iterated exponentiation
+        for (2 .. $b) { $result = 1 << $result }    # 2 ** $result
+    } else {
+        # $n > 4 means iterated hyper...
+        $result = _twohyper( $n - 1, 2 );
+        if ($b > 2) {
+            for (3 .. $b) { $result = _twohyper( $n - 1, $result ) }
+        }
+    }
+    say "2hyper( $n, $b ) = ", $result if $trace;
+    return $result;
+}
+sub ack2 ( $m, $n ) {
+    die "the function is not defined for negative parameters" if $m < 0 || $n < 0;
+    if (defined my $nlimit = $limits{$m}) {
+        warn "this may run out of memory..." if $n > $nlimit;
+    }
+    return _twohyper($m, $n + 3) - 3;
+}
+
+unless (@ARGV) {
+    _test();
+    exit(0);
+}
+die "must give two nonnegative integers as input" unless @ARGV > 1;
+
+$" = ', ';
+my $result = ack2(@ARGV);
+my $desc = $result->length < 78 ? $result :
+    sprintf 'int with %u digits', length($result);
+say "A( @ARGV ) = ", $desc;
+
+
+sub _test {
+    for my $m (0 .. 5) {
+        my $nlimit = $limits{$m} // 5;
+        for my $n (0 .. $nlimit) {
+            my $result = ack2($m, $n);
+            my $desc = $result->length < 78 ? $result :
+                sprintf 'int with %u digits', length($result);
+            say "A( $m, $n ) = ", $desc;
+        }
+    }
+}
+