Solution to task #2 challenge-077.

1 files changed, 101 insertions, 0 deletions

diff --git a/challenge-077/wanderdoc/perl/ch-2.pl b/challenge-077/wanderdoc/perl/ch-2.pl
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+++ b/challenge-077/wanderdoc/perl/ch-2.pl
@@ -0,0 +1,101 @@
+#!perl
+use strict;
+use warnings FATAL => qw(all);
+
+=prompt
+You are given m x n character matrix consists of O and X only. Write a script to count the total number of X surrounded by O only. Print 0 if none found.
+Example 1: Input: [ O O X ] [ X O O ] [ X O O ]
+Output: 1 as there is only one X at the first row last column surrounded by only O.
+Example 2: Input: [ O O X O ] [ X O O O ] [ X O O X ] [ O X O O ]
+Output: 2 a) First  X found at Row 1 Col 3. b) Second X found at Row 3 Col 4.
+=cut
+
+
+
+
+
+
+
+for my $test ( [[ qw(O O X) ], [ qw(X O O) ], [ qw(X O O) ]],
+     [[ qw(O O X O) ], [ qw(X O O O) ], [ qw(X O O X) ], [ qw(O X O O) ]],
+     [[ qw(O O X) ], [ qw(X O X) ], [ qw(X O O) ]]) 
+{
+     output_lonely($test);
+}     
+
+
+sub output_lonely
+{
+     my $aref = $_[0];
+     my @result = _find_lonely($aref);
+
+     my $counter = 0; 
+
+     if ( @result )
+     {
+          print ++$counter, ': ', join(",", @$_), $/ for @result;
+     }
+
+
+
+     else
+     {
+          print 0, $/;
+     }
+     print $/;
+}
+
+
+
+sub _find_lonely
+{
+     my $aref = $_[0];
+     my $m = $#$aref;
+     my $n = $#{$aref->[0]};
+     my @x_shift = (-1, 0, 1);
+     my @y_shift = (-1, 0, 1);
+     my @lonely;
+
+     for my $row_idx ( 0 .. $m )
+     {
+          TEST: for my $col_idx ( 0 .. $n )
+          {
+               next if $aref->[$row_idx][$col_idx] eq 'O';
+
+               for my $xs ( @x_shift )
+               {
+
+                    for my $ys ( @y_shift )
+                    {
+                         next if 0 == $xs and 0 == $ys;
+                         my $neighbor_y = $row_idx + $ys;
+                         my $neighbor_x = $col_idx + $xs;
+
+                         if ( _is_valid( $m, $n, $neighbor_y, $neighbor_x ) )
+                         {
+
+                              next TEST if $aref->[$neighbor_y][$neighbor_x] eq 'X';
+                         }
+
+                    }
+               }
+               push @lonely, [$row_idx, $col_idx];
+          }
+     }
+
+     return @lonely;
+}
+
+
+sub _is_valid
+{
+     my ( $m, $n, $y, $x ) = @_;
+
+
+     if ( $y >= 0 and $y <= $m and $x >= 0 and $x <= $n )
+     {
+          return 1;
+     }
+
+     return 0;
+}
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