Merge pull request #395 from oWnOIzRi/week017

add script for task 1

1 files changed, 53 insertions, 0 deletions

diff --git a/challenge-017/steven-wilson/perl5/ch-1.pl b/challenge-017/steven-wilson/perl5/ch-1.pl
new file mode 100644
index 0000000000..7aa4cdb3c1
--- /dev/null
+++ b/challenge-017/steven-wilson/perl5/ch-1.pl
@@ -0,0 +1,53 @@
+#!/usr/bin/env perl
+# Author: Steven Wilson
+# Date: 2019-07-15
+# Week: 017
+#
+# Task #1
+# Create a script to demonstrate Ackermann function. The Ackermann
+# function is defined as below, m and n are positive number:
+#   A(m, n) = n + 1                  if m = 0
+#   A(m, n) = A(m - 1, 1)            if m > 0 and n = 0
+#   A(m, n) = A(m - 1, A(m, n - 1))  if m > 0 and n > 0
+# Example expansions as shown in wiki page.
+# https://en.wikipedia.org/wiki/Ackermann_function
+#  A(1, 2) = A(0, A(1, 1))
+#          = A(0, A(0, A(1, 0)))
+#          = A(0, A(0, A(0, 1)))
+#          = A(0, A(0, 2))
+#          = A(0, 3)
+#          = 4
+
+use strict;
+use warnings;
+use Memoize;
+no warnings 'recursion';
+use feature qw/ say /;
+use Test::More;
+
+ok( A( 1, 2 ) == 4, 'Test A(1, 2) == 4' );
+
+done_testing();
+
+# This gets past A(4,1) quicker but A(4,2) takes too long so don't run this script
+memoize("A");
+
+sub A {
+    my ( $m, $n ) = @_;
+    if ( $m == 0 ) {
+        return $n + 1;
+    }
+    elsif ( $m > 0 and $n == 0 ) {
+        return A( $m - 1, 1 );
+    }
+    elsif ( $m > 0 and $n > 0 ) {
+        return A( $m - 1, A( $m, $n - 1 ) );
+    }
+}
+
+my $number = 4;
+for my $n ( 0 .. $number ) {
+    for my $m ( 0 .. $number ) {
+        say "A($m, $n) is ".  A( $m, $n );
+    }
+}