Simon's solution to challenge 72

4 files changed, 85 insertions, 14 deletions

diff --git a/challenge-072/sgreen/README.md b/challenge-072/sgreen/README.md
index 0f43e97b94..6dec32d966 100644
--- a/challenge-072/sgreen/README.md
+++ b/challenge-072/sgreen/README.md
@@ -1,27 +1,39 @@
-# Perl Weekly Challenge 070
+# Perl Weekly Challenge 072
 
 Solution by Simon Green.
 
- 
-## TASK #1 › Character Swapping
+No solutions for last week as I was moving interstate. I'm back on board this week :)
 
-For this I used the fact that `($a, $b) = ($b, a)` does what it should. Therefore it was a simple exercise of  doing this for `$C` times, and then display the output.
+## TASK #1 › Trailing Zeroes
 
-The task states that `$C + $O <= $O`. This however is not possible. When `$C + $O = $N`, you will get a `substr outside of string` error. For this reason, I've only allowed `$C + $O < $N` to be valid.
+When you think about it, a trailing zero is a product of 10, which is 2 × 5. Forgetting about the twos (since every second number is even), the five occurs every 5 numbers. Thus the factorial from 1 to 4 will contain no trailing zeros, 5-9 one trailing zero, 10-14 three trailing zeros, and so on. Once you reach 25, it gets a little more complicated as 25 is 5 × 5. Anyway, I digress from the actual task.
 
-### Example
+For this task, I take the input, calculate the factorial value, I then use a regular expression to find the trailing zeros (if any), and then display it.
 
-    » ./ch-1.pl perlandraku 3 4
-    pndraerlaku
+### Examples
 
-    » perl/ch-1.pl helloworld 8 1
-    hlloworlde
+    » ./ch-1.pl 10
+    2
 
-## TASK 2 › Gray Code Sequence
+    » ./ch-1.pl 7
+    1
 
-Not really much to say about this task, as it is string forward. Given that `$N` can not be greater than five, I simply stored the array in memory. Even at 24 bits, it will run without any issues.
+    » ./ch-1.pl 4
+    0
+
+## TASK 2 › Lines Range
+
+This tasks was relatively simple. Read the file, skip the lines < `$A` and exit the loop once line `$B` is reached (or the end of file).
 
 ## Example
 
-    » ./ch-2.pl 4
-    0 1 3 2 6 7 5 4 12 13 15 14 10 11 9 8
+    » ./ch-2.pl input.txt 4 12
+    L4
+    L5
+    L6
+    L7
+    L8
+    L9
+    L10
+    L11
+    L12
\ No newline at end of file
diff --git a/challenge-072/sgreen/blog.txt b/challenge-072/sgreen/blog.txt
new file mode 100644
index 0000000000..71fedf0051
--- /dev/null
+++ b/challenge-072/sgreen/blog.txt
@@ -0,0 +1 @@
+https://github.com/manwar/perlweeklychallenge-club/blob/master/challenge-072/sgreen/README.md
diff --git a/challenge-072/sgreen/perl/ch-1.pl b/challenge-072/sgreen/perl/ch-1.pl
new file mode 100755
index 0000000000..a3836ffa0a
--- /dev/null
+++ b/challenge-072/sgreen/perl/ch-1.pl
@@ -0,0 +1,20 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use 5.10.1;
+
+sub main (@) {
+    my $N = shift;
+
+    # Calculate N!
+    my $total = 1;
+    $total *= $_ for ( 1 .. $N );
+
+    # Strip out everything except the last zeros (if any)
+    # And display the length of the string
+    $total =~ /^.*?(0*)$/;
+    say length($1);
+}
+
+main(@ARGV);
diff --git a/challenge-072/sgreen/perl/ch-2.pl b/challenge-072/sgreen/perl/ch-2.pl
new file mode 100755
index 0000000000..37c5060596
--- /dev/null
+++ b/challenge-072/sgreen/perl/ch-2.pl
@@ -0,0 +1,38 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use 5.10.1;
+
+sub main (@) {
+    my ( $file, $start, $end ) = @_;
+
+    # Sanity check
+    die "File '$file' does not exist or is not readable\n" unless -r $file;
+    die "The start value must be a positive number\n"
+      unless $start =~ /^[0-9]+$/;
+    die "The end value must be a positive number\n" unless $end =~ /^[0-9]+$/;
+    die "The start value cannot be greater than the end value\n"
+      if $start > $end;
+
+    # Open the file
+    open( my $fh, '<', $file ) or die $!;
+
+    my $cnt = 0;
+    while ( my $line = <$fh> ) {
+        ++$cnt;
+
+        # We don't print lines before $start
+        next if $cnt < $start;
+
+        print $line;
+
+        # Likewise, if we have reached $end, their is nothing more to print
+        last if $cnt == $end;
+    }
+
+    close $fh;
+
+}
+
+main(@ARGV);