1 files changed, 55 insertions, 0 deletions
diff --git a/challenge-079/bob-lied/perl/lib/CountSetBit.pm b/challenge-079/bob-lied/perl/lib/CountSetBit.pm
new file mode 100644
index 0000000000..1733d4e676
--- /dev/null
+++ b/challenge-079/bob-lied/perl/lib/CountSetBit.pm
@@ -0,0 +1,55 @@
+# vim:set ts=4 sw=4 sts=4 et ai wm=0 nu:
+#=============================================================================
+# CountSetBit.pm
+#=============================================================================
+# Copyright (c) 2020, Bob Lied
+#=============================================================================
+# Description:
+#=============================================================================
+
+package CountSetBit;
+
+use strict;
+use warnings;
+use v5.30;
+
+use feature qw/ signatures /;
+no warnings qw/ experimental::signatures /;
+
+require Exporter;
+our @ISA = qw(Exporter);
+our @EXPORT = qw();
+our @EXPORT_OK = qw();
+
+sub new($class, $n)
+{
+    $class = ref($class) || $class;
+    my $self = {
+        _n => $n,
+
+        _sum => 0,
+    };
+    bless $self, $class;
+    return $self;
+}
+
+# https://www.techiedelight.com/brian-kernighans-algorithm-count-set-bits-integer/
+sub run($self)
+{
+    $self->{_sum} += $self->_bitsOf($_) for ( 1 .. $self->{_n} );
+    return ( $self->{_sum} % 1000000007 );
+}
+
+sub _bitsOf($self, $n)a
+{
+    my $count = 0;
+
+    while ( $n > 0 )
+    {
+        $count++;
+        $n = $n & ($n-1);
+    }
+    return $count;
+}
+
+1;