Simon's solution to challenge 248

6 files changed, 143 insertions, 1 deletions

diff --git a/challenge-248/sgreen/README.md b/challenge-248/sgreen/README.md
index 191a192e6e..296c098161 100644
--- a/challenge-248/sgreen/README.md
+++ b/challenge-248/sgreen/README.md
@@ -1,3 +1,3 @@
 # The Weekly Challenge 247
 
-Blog: [The one about frequency](https://dev.to/simongreennet/the-one-about-frequency-la6)
+Blog: [A string, a character and a matrix...](https://dev.to/simongreennet/a-string-a-character-and-a-matrix-5bc9)
diff --git a/challenge-248/sgreen/blog.txt b/challenge-248/sgreen/blog.txt
new file mode 100644
index 0000000000..1a8b90ac22
--- /dev/null
+++ b/challenge-248/sgreen/blog.txt
@@ -0,0 +1 @@
+https://dev.to/simongreennet/a-string-a-character-and-a-matrix-5bc9
\ No newline at end of file
diff --git a/challenge-248/sgreen/perl/ch-1.pl b/challenge-248/sgreen/perl/ch-1.pl
new file mode 100755
index 0000000000..701b20f191
--- /dev/null
+++ b/challenge-248/sgreen/perl/ch-1.pl
@@ -0,0 +1,40 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature 'say';
+use experimental 'signatures';
+
+sub main ( $word, $char ) {
+    # Obtain the positions of the character in the string
+    my @positions = ();
+    foreach my $i ( 0 .. length($word) - 1 ) {
+        push @positions, $i if substr( $word, $i, 1 ) eq $char;
+    }
+
+    if ( $#positions == -1 ) {
+        # Throw an error if we don't find the character in the string
+        die "'$char' does not appear in string\n";
+    }
+
+    # Record the position of the first occurrence of the character, and the next
+    my $current_pos = shift(@positions);
+    my $next_pos    = shift(@positions) // $current_pos;
+
+    my @solution = ();
+    foreach my $i ( 0 .. length($word) - 1 ) {
+        if ( abs( $i - $next_pos ) < abs( $i - $current_pos ) ) {
+            # We are closer to the next occurrence of the character
+            $current_pos = $next_pos;
+            $next_pos    = shift(@positions) // $current_pos;
+        }
+
+        # Record the closest occurrence for this position
+        push @solution, abs( $i - $current_pos );
+    }
+
+    # Print the solution
+    say '(', join( ',', @solution ), ')';
+}
+
+main(@ARGV);
\ No newline at end of file
diff --git a/challenge-248/sgreen/perl/ch-2.pl b/challenge-248/sgreen/perl/ch-2.pl
new file mode 100755
index 0000000000..38e26033a7
--- /dev/null
+++ b/challenge-248/sgreen/perl/ch-2.pl
@@ -0,0 +1,37 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature 'say';
+use experimental 'signatures';
+
+use JSON 'decode_json';
+
+sub main ($matrix) {
+    # Calculate the size of the matrix
+    my $cols = scalar( @{ $matrix->[0] } );
+
+    # Check that all columns are of equal length
+    foreach my $r ( 1 .. $#$matrix ) {
+        if ( scalar( @{ $matrix->[$r] } ) != $cols ) {
+            die "Row $r has different number of columns\n";
+        }
+    }
+
+    say '[';
+    foreach my $r ( 0 .. $#$matrix - 1) {
+        # Compute each row
+        my @row = ();
+        foreach my $c ( 0 .. $cols - 2 ) {
+            push @row,
+              $matrix->[$r][$c] +
+              $matrix->[$r][ $c + 1 ] +
+              $matrix->[ $r + 1 ][$c] +
+              $matrix->[ $r + 1 ][ $c + 1 ];
+        }
+        say '  [', join( ', ', @row ), '],';
+    }
+    say ']';
+}
+
+main( decode_json( $ARGV[0] ) );
\ No newline at end of file
diff --git a/challenge-248/sgreen/python/ch-1.py b/challenge-248/sgreen/python/ch-1.py
new file mode 100755
index 0000000000..2a236bacf4
--- /dev/null
+++ b/challenge-248/sgreen/python/ch-1.py
@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+
+import sys
+
+
+def main(word, char):
+    # Obtain the positions of the character in the string
+    positions = [i for i, s in enumerate(word) if s == char]
+
+    if len(positions) == 0:
+        # Throw an error if we don't find the character in the string
+        raise ValueError(f"'{char}' does not appear in string")
+
+    # Record the position of the first occurrence of the character, and the next
+    current_pos = positions.pop(0)
+    next_pos = positions.pop(0) if len(positions) > 0 else current_pos
+
+    solution = []
+    for i in range(len(word)):
+        if abs(i - next_pos) < abs(i-current_pos):
+            # We are closer to the next occurrence of the character
+            current_pos = next_pos
+            next_pos = positions.pop(0) if len(positions) > 0 else current_pos
+
+        # Record the closest occurrence for this position
+        solution.append(abs(i-current_pos))
+
+    # Print the solution
+    print('(' + ','.join(map(str, solution)) + ')')
+
+
+if __name__ == '__main__':
+    main(*sys.argv[1:])
diff --git a/challenge-248/sgreen/python/ch-2.py b/challenge-248/sgreen/python/ch-2.py
new file mode 100755
index 0000000000..47eba6db2d
--- /dev/null
+++ b/challenge-248/sgreen/python/ch-2.py
@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+
+import json
+import sys
+
+
+def main(matrix):
+    # Calculate the size of the matrix
+    rows = len(matrix)
+    cols = len(matrix[0])
+
+    # Check that all columns are of equal length
+    for r in range(1, rows):
+        if len(matrix[r]) != cols:
+            raise ValueError(f'Row {r} has different number of columns')
+
+    print('[')
+    for r in range(rows-1):
+        # Compute each row
+        row = []
+        for c in range(cols-1):
+            row.append(matrix[r][c] + matrix[r][c+1] +
+                       matrix[r+1][c] + matrix[r+1][c+1])
+        print('  ' + str(row) + ',')
+
+    print(']')
+
+
+if __name__ == '__main__':
+    # Read the input as JSON
+    main(json.loads(sys.argv[1]))