From 656b809b747b8b8081b4f5a9a8d93d3c6703a6d0 Mon Sep 17 00:00:00 2001
From: Niels van Dijke <perlboy@cpan.org>
Date: Tue, 22 Sep 2020 17:41:47 +0000
Subject: Task 1 & 2

---
 challenge-079/perlboy1967/perl/ch-1.pl |  39 +++++++++++
 challenge-079/perlboy1967/perl/ch-2.pl | 117 +++++++++++++++++++++++++++++++++
 2 files changed, 156 insertions(+)
 create mode 100755 challenge-079/perlboy1967/perl/ch-1.pl
 create mode 100755 challenge-079/perlboy1967/perl/ch-2.pl

diff --git a/challenge-079/perlboy1967/perl/ch-1.pl b/challenge-079/perlboy1967/perl/ch-1.pl
new file mode 100755
index 0000000000..911cda875d
--- /dev/null
+++ b/challenge-079/perlboy1967/perl/ch-1.pl
@@ -0,0 +1,39 @@
+#!/usr/bin/perl
+
+# Perl Weekly Challenge - 079
+# - https://perlweeklychallenge.org/blog/perl-weekly-challenge-079/
+#
+# Task 1 - Count Set Bits
+#
+# Author: Niels 'PerlBoy' van Dijke
+
+use strict;
+use warnings;
+
+use constant SOME_VALUE => 1000000007;
+
+my ($N) = @ARGV;
+
+die "N must be positive integer value"
+  unless (defined $N and $N =~ m#^[1-9][0-9]*$#);
+
+my $bits = countBits($N);
+
+printf "Input: %d\n", $N;
+printf "Output: %d %% %d = %d\n", 
+       $bits, 
+       SOME_VALUE(), 
+       $bits % SOME_VALUE();
+
+sub countBits {
+  my ($n) = @_;
+
+  my $b = 0;
+
+  map {
+    # Some 'unpack/pack' black magic
+    $b += unpack('%32b*', pack('I', $_));
+  } (1 .. $n);
+
+  return $b;
+}
diff --git a/challenge-079/perlboy1967/perl/ch-2.pl b/challenge-079/perlboy1967/perl/ch-2.pl
new file mode 100755
index 0000000000..04f6c69762
--- /dev/null
+++ b/challenge-079/perlboy1967/perl/ch-2.pl
@@ -0,0 +1,117 @@
+#!/usr/bin/perl
+
+# Perl Weekly Challenge - 079
+# - https://perlweeklychallenge.org/blog/perl-weekly-challenge-079/
+#
+# Task 2 - Trapped Rain Water
+#
+# Author: Niels 'PerlBoy' van Dijke
+
+use strict;
+use warnings;
+
+use List::Util qw(min max);
+use List::MoreUtils qw(uniq indexes);
+
+
+my (@N) = @ARGV;
+@N = (1, 2, 1, 1, 10, 3, 4, 1, 2, 7, 2, 2, 4, 1, 2, 1, 3, 2) 
+  unless scalar @N;
+
+die "N must be a list of at least 3 positive integer values"
+  unless (scalar @N >= 3 and !scalar(grep { !/^[1-9][0-9]*$/ } @N));
+
+
+my $grid = createHistGrid(\@N);
+printHistogram('Input:', $grid, \@N);
+my $trappedWater = findAndFillGaps(\@N, $grid);
+printHistogram('Output:', $grid, \@N, $trappedWater);
+
+
+sub createHistGrid {
+  my ($arList) = @_;
+
+  my $grid = [];
+
+  my $max = max(@$arList);
+
+  foreach my $y (0 .. $max - 1) {
+    foreach my $x (0 .. scalar @$arList - 1) {
+      $grid->[$x][$y] = ($arList->[$x] > $y ? '#' : ' ');
+    }
+  }
+
+  return $grid;
+}      
+
+
+sub findAndFillGaps {
+  my ($arL, $grid) = @_;
+
+  my $dropsAdded = 0;
+
+  my @list = @$arL;
+
+  my @levels = sort {$b <=> $a } uniq(@list);
+
+  foreach my $level (@levels) {
+    my @i = indexes { $_ >= $level } @list;
+    next unless (scalar(@i) > 1);
+
+    do {
+      my $i = shift(@i);
+      last if (!defined $i[0]);
+
+      if ($i[0] - $i > 1) {
+        my $fillLevel = min($list[$i], $list[$i[0]]);
+
+        for my $j ($i + 1 .. $i[0] - 1) { 
+          for my $k ($list[$j] + 1 .. $fillLevel) {
+            $grid->[$j][$k - 1] = '.';
+          }
+          $dropsAdded += ($fillLevel - $list[$j]);
+          $list[$j] = $fillLevel;
+        }
+      }
+    } while (scalar @i > 1);
+  }
+
+  return $dropsAdded;
+}
+
+
+sub printHistogram {
+  my ($caption, $arGrid, $arList, $trappedWater) = @_;
+
+  my $max = max(@$arList);
+  my $yLw = length($max);
+
+  print "$caption\n";
+
+  # Print histogram rows
+  for (my $row = $max; $row > 0; $row--) {
+    my @row = (sprintf("%${yLw}s", $row), '|');
+    for my $col (0 .. scalar(@$arList) - 1) {
+      push(@row, $grid->[$col][$row - 1]);
+    }
+    print join(" ", @row)."\n";
+  }
+
+  # Print X-axis
+  print sprintf("%${yLw}s +%s\n",
+                '',
+                join('-', map { '-' } @$arList, ''));
+
+  # Print X labels
+  for my $l (0 .. $yLw - 1) {
+    print sprintf("%${yLw}s   %s\n",
+                  '',
+                  join(' ', map { substr($_.' ' x $yLw, $l, 1) } @$arList));
+  }
+
+  if (defined $trappedWater) {
+    printf "\nAmount of trapped waterdrops: %d (marked with '.' in histogram).\n", $trappedWater;
+  }
+
+  print "\n";
+}
-- 
cgit