A-M baby

Task/Hailstone-sequence/Perl/hailstone-sequence-1.pl

@@ -0,0 +1,37 @@
+#!/usr/bin/perl
+
+use warnings;
+use strict;
+
+my @h = hailstone(27);
+print "Length of hailstone(27) = " . scalar @h . "\n";
+print "[" . join(", ", @h[0 .. 3], "...", @h[-4 .. -1]) . "]\n";
+
+my ($max, $n) = (0, 0);
+for my $x (1 .. 99_999) {
+    @h = hailstone($x);
+    if (scalar @h > $max) {
+        ($max, $n) = (scalar @h, $x);
+    }
+}
+
+print "Max length $max was found for hailstone($n) for numbers < 100_000\n";
+
+
+sub hailstone {
+    my ($n) = @_;
+
+    my @sequence = ($n);
+
+    while ($n > 1) {
+        if ($n % 2 == 0) {
+            $n = int($n / 2);
+        } else {
+            $n = $n * 3 + 1;
+        }
+
+        push @sequence, $n;
+    }
+
+    return @sequence;
+}

Task/Hailstone-sequence/Perl/hailstone-sequence-2.pl

@@ -0,0 +1,15 @@
+#!/usr/bin/perl
+use strict;
+
+sub hailstone {
+    @_ = local $_ = shift;
+    push @_, $_ = $_ % 2 ? 3 * $_ + 1 : $_ / 2 while $_ > 1;
+    @_;
+}
+
+my @h = hailstone($_ = 27);
+print "$_: @h[0 .. 3] ... @h[-4 .. -1] (".@h.")\n";
+
+@h = ();
+for (1 .. 99_999) { @h = ($_, $h[2]) if ($h[2] = hailstone($_)) > $h[1] }
+printf "%d: (%d)\n", @h;

Task/Hailstone-sequence/Perl/hailstone-sequence-3.pl

@@ -0,0 +1,3 @@
+sub _{my$_=$_[''];push@_,$_&1?$_+=$_++<<1:($_>>=1)while$_^1;@_}
+@_=_($_=031^2);print "$_: @_[0..3] ... @_[-4..-1] (".@_.")\n";
+$_[1]<($_[2]=_($_))and@_=($_,$_[2])for 1..1e5-1;printf "%d: (%d)\n", @_;