2 files changed, 99 insertions, 0 deletions
diff --git a/challenge-248/paulo-custodio/perl/ch-2.pl b/challenge-248/paulo-custodio/perl/ch-2.pl
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+++ b/challenge-248/paulo-custodio/perl/ch-2.pl
@@ -0,0 +1,80 @@
+#!/usr/bin/env perl
+
+# Challenge 248
+#
+# Task 2: Submatrix Sum
+# Submitted by: Jorg Sommrey
+# You are given a NxM matrix A of integers.
+#
+# Write a script to construct a (N-1)x(M-1) matrix B having elements that are the sum over the 2x2 submatrices of A,
+#
+# b[i,k] = a[i,k] + a[i,k+1] + a[i+1,k] + a[i+1,k+1]
+#
+# Example 1
+# Input: $a = [
+#               [1,  2,  3,  4],
+#               [5,  6,  7,  8],
+#               [9, 10, 11, 12]
+#             ]
+#
+# Output: $b = [
+#                [14, 18, 22],
+#                [30, 34, 38]
+#              ]
+# Example 2
+# Input: $a = [
+#               [1, 0, 0, 0],
+#               [0, 1, 0, 0],
+#               [0, 0, 1, 0],
+#               [0, 0, 0, 1]
+#             ]
+#
+# Output: $b = [
+#                [2, 1, 0],
+#                [1, 2, 1],
+#                [0, 1, 2]
+#              ]
+
+use Modern::Perl;
+
+my $matrix = parse_matrix("@ARGV");
+my $sums = sum_submatrices($matrix);
+print_matrix($sums);
+
+sub parse_matrix {
+    my($text) = @_;
+    my @lines = split(/\]\s*,/, $text);
+    my $matrix = [];
+    for (@lines) {
+        s/^\D+//;
+        my @nums = split /\D+/, $_;
+        push @$matrix, \@nums;
+    }
+    return $matrix;
+}
+
+sub sum_submatrices {
+    my($matrix) = @_;
+    my $sums = [];
+    my $rows = scalar(@$matrix);
+    my $cols = scalar(@{$matrix->[0]});
+    for my $r (0 .. $rows-2) {
+        for my $c (0 .. $cols-2) {
+            $sums->[$r][$c] = 0;
+            $sums->[$r][$c] += $matrix->[$r][$c];
+            $sums->[$r][$c] += $matrix->[$r][$c+1];
+            $sums->[$r][$c] += $matrix->[$r+1][$c];
+            $sums->[$r][$c] += $matrix->[$r+1][$c+1];
+        }
+    }
+    return $sums;
+}
+
+sub print_matrix {
+    my($matrix) = @_;
+    say "[";
+    for (@$matrix) {
+        say "  [", join(", ", @$_), "],";
+    }
+    say "]";
+}
diff --git a/challenge-248/paulo-custodio/t/test-2.yaml b/challenge-248/paulo-custodio/t/test-2.yaml
new file mode 100644
index 0000000000..ca5e38be19
--- /dev/null
+++ b/challenge-248/paulo-custodio/t/test-2.yaml
@@ -0,0 +1,19 @@
+- setup:
+  cleanup:
+  args:     '[ [1,  2,  3,  4], [5,  6,  7,  8], [9, 10, 11, 12] ]'
+  input:
+  output:   |
+            |[
+            |  [14, 18, 22],
+            |  [30, 34, 38],
+            |]
+- setup:
+  cleanup:
+  args:     '[ [1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 0], [0, 0, 0, 1] ]'
+  input:
+  output:   |
+            |[
+            |  [2, 1, 0],
+            |  [1, 2, 1],
+            |  [0, 1, 2],
+            |]