Solutions for PWC 079

2 files changed, 93 insertions, 6 deletions

diff --git a/challenge-079/bob-lied/perl/lib/CountSetBit.pm b/challenge-079/bob-lied/perl/lib/CountSetBit.pm
index 37f74ea838..1733d4e676 100644
--- a/challenge-079/bob-lied/perl/lib/CountSetBit.pm
+++ b/challenge-079/bob-lied/perl/lib/CountSetBit.pm
@@ -21,19 +21,35 @@ our @ISA = qw(Exporter);
 our @EXPORT = qw();
 our @EXPORT_OK = qw();
 
-sub new($class, $name1)
+sub new($class, $n)
 {
     $class = ref($class) || $class;
     my $self = {
-        _name1 => $name1,
+        _n => $n,
+
+        _sum => 0,
     };
     bless $self, $class;
     return $self;
 }
 
+# https://www.techiedelight.com/brian-kernighans-algorithm-count-set-bits-integer/
 sub run($self)
 {
-    return undef;
+    $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;
diff --git a/challenge-079/bob-lied/perl/lib/TrappedRainWater.pm b/challenge-079/bob-lied/perl/lib/TrappedRainWater.pm
index cb98286764..34285e52b9 100644
--- a/challenge-079/bob-lied/perl/lib/TrappedRainWater.pm
+++ b/challenge-079/bob-lied/perl/lib/TrappedRainWater.pm
@@ -16,24 +16,95 @@ use v5.30;
 use feature qw/ signatures /;
 no warnings qw/ experimental::signatures /;
 
+use List::Util qw/ max /;
+
 require Exporter;
 our @ISA = qw(Exporter);
 our @EXPORT = qw();
 our @EXPORT_OK = qw();
 
-sub new($class, $name1)
+sub new($class, $listref)
 {
     $class = ref($class) || $class;
     my $self = {
-        _name1 => $name1,
+        _list => $listref,
+        _numCol => scalar(@$listref),
+        _numRow => List::Util::max(@$listref),
+
+        _grid => [],
+        _trap => [],
     };
     bless $self, $class;
+
+    $self->_setup();
     return $self;
 }
 
+sub _setup($self)
+{
+    my ($lst, $trap, $g, $numRow, $numCol) = @{$self}{ qw(_list _trap _grid _numRow _numCol) };
+
+    for ( my $r = 0; $r < $numRow ; $r++ )
+    {
+        for ( my $c = 0; $c < $numCol; $c++ )
+        {
+            $g->[$r][$c] = ( $lst->[$c] > $r ? '#' : ' ');
+            $trap->[$r][$c] = 0;
+        }
+    }
+}
+
+sub show($self)
+{
+    my ($g, $numRow, $numCol) = @{$self}{ qw(_trap _numRow _numCol) };
+    print "    ";
+    for ( my $c = 0 ; $c < $numCol; $c++ )
+    {
+        print "[$c]";
+    }
+    print "\n";
+    for ( my $r = $numRow - 1; $r >= 0 ; $r-- )
+    {
+        print "[$r] ";
+        say " ", join('  ', @{$g->[$r]}), " ";
+    }
+
+}
+
+sub _hasWall($self)
+{
+    my $sawWall = 0;
+    my $g = $self->{_grid};
+    my $trap = $self->{_trap};
+
+    for (my $r = 0 ; $r < $self->{_numRow} ; $r++ )
+    {
+        # Increment count if there's a wall on the left
+        for (my $c = 0 ; $c < $self->{_numCol} ; $c++ )
+        {
+            if    ( $g->[$r][$c] eq '#' ) { $sawWall = 1 }
+            elsif ( $sawWall )            { $trap->[$r][$c]++ }
+        }
+        # Increment count if there's a wall on the right
+        $sawWall = 0;
+        for (my $c = $self->{_numCol}-1 ; $c >= 0 ; $c-- )
+        {
+            if    ( $g->[$r][$c] eq '#' ) { $sawWall = 1 }
+            elsif ( $sawWall )            { $trap->[$r][$c]++ }
+        }
+        $sawWall = 0;
+    }
+    # Assume there's a wall on the bottom (all list values are > 0).
+}
+
 sub run($self)
 {
-    return undef;
+    $self->_hasWall();
+
+    my @flattrap = map { ref eq 'ARRAY' ? @$_ : $_ } @{$self->{_trap}};
+
+    my $holdsWater = grep { $_ == 2 } @flattrap;
+    return $holdsWater;
 }
 
 1;