add solutions for challenge-079

3 files changed, 118 insertions, 0 deletions

diff --git a/challenge-079/alexander-pankoff/README b/challenge-079/alexander-pankoff/README
index 41f67807ac..f1aacf3dba 100644
--- a/challenge-079/alexander-pankoff/README
+++ b/challenge-079/alexander-pankoff/README
@@ -1 +1,6 @@
 Solution by Alexander Pankoff
+
+# ch-1
+
+Aproach taken from:
+https://www.geeksforgeeks.org/count-total-set-bits-in-all-numbers-from-1-to-n/
diff --git a/challenge-079/alexander-pankoff/perl/ch-1.pl b/challenge-079/alexander-pankoff/perl/ch-1.pl
new file mode 100755
index 0000000000..98d0f946a5
--- /dev/null
+++ b/challenge-079/alexander-pankoff/perl/ch-1.pl
@@ -0,0 +1,42 @@
+#!/usr/bin/env perl
+use v5.20;
+use utf8;
+use strict;
+use warnings;
+use autodie;
+use feature qw(say signatures);
+no warnings 'experimental::signatures';
+#
+# You are given a positive number $N.
+#
+# Write a script to count the total numbrer of set bits of the binary
+# representations of all numbers from 1 to $N and return
+# $total_count_set_bit % 1000000007.
+
+my ($N) = @ARGV;
+
+say count_set_bits($N) % 1000000007;
+
+sub count_set_bits($n) {
+    my $count = 0;
+    my $i     = 0;
+
+    while ( (1 << $i) <= $n ) {
+        my $set          = 0;
+        my $change_after = 1 << $i;
+        for ( 0 .. $n ) {
+            $count += $set;
+            if ( $change_after == 1 ) {
+                $set          = !$set;
+                $change_after = 1 << $i;
+            }
+            else {
+                $change_after--;
+
+            }
+        }
+        $i++;
+    }
+
+    return $count;
+}
diff --git a/challenge-079/alexander-pankoff/perl/ch-2.pl b/challenge-079/alexander-pankoff/perl/ch-2.pl
new file mode 100755
index 0000000000..2287d6d220
--- /dev/null
+++ b/challenge-079/alexander-pankoff/perl/ch-2.pl
@@ -0,0 +1,71 @@
+#!/usr/bin/env perl
+use v5.20;
+use utf8;
+use strict;
+use warnings;
+use autodie;
+use feature qw(say signatures);
+no warnings 'experimental::signatures';
+
+use List::Util qw(min max sum0 head);
+
+# You are given an array of positive numbers @N.
+#
+# Write a script to represent it as Histogram Chart and find out how much water it can trap.
+
+use constant DEBUG => $ENV{DEBUG} // 0;
+
+my @N = @ARGV;
+
+print_chart(@N);
+say calculate_volume(@N);
+
+sub calculate_volume(@chart) {
+
+    my $volume = 0;
+    my $last   = 0;
+    my @bucket;
+
+    for my $i ( 0 .. $#chart ) {
+
+        my $cur = $chart[$i];
+        if ( !@bucket && $last > $cur ) {
+            push @bucket, $last;
+        }
+
+        if (@bucket) {
+            push @bucket, $cur;
+            if ( $cur >= $bucket[0] || $cur >= max( @chart[ $i .. $#chart ] ) )
+            {
+                $volume += bucket_volume(@bucket);
+                @bucket = ();
+            }
+        }
+
+        $last = $cur;
+        $i++;
+    }
+
+    return $volume;
+
+}
+
+sub bucket_volume(@bucket) {
+
+    my $lwall         = shift(@bucket);
+    my $rwall         = pop(@bucket);
+    my $bucket_height = min( $lwall, $rwall );
+    return sum0( map { $bucket_height - $_ } @bucket );
+}
+
+sub print_chart (@chart) {
+
+    my $height = max(@chart);
+
+    for my $line ( reverse( 1 .. $height ) ) {
+        say join( " ", $line, ( map { $_ < $line ? ' ' : '#' } @chart ) );
+    }
+
+    say join( "-", map { '-' } 1, @chart );
+    say join( " ", ' ', @chart );
+}