new file: challenge-340/mattneleigh/perl/ch-1.pl

new file:   challenge-340/mattneleigh/perl/ch-2.pl

2 files changed, 149 insertions, 0 deletions

diff --git a/challenge-340/mattneleigh/perl/ch-1.pl b/challenge-340/mattneleigh/perl/ch-1.pl
new file mode 100755
index 0000000000..c25026044f
--- /dev/null
+++ b/challenge-340/mattneleigh/perl/ch-1.pl
@@ -0,0 +1,61 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @strings = (
+    "abbaca",
+    "azxxzy",
+    "aaaaaaaa",
+    "aabccba",
+    "abcddcba"
+);
+
+print("\n");
+foreach my $string (@strings){
+    printf(
+        "Input: \$str = '%s'\nOutput: '%s'\n\n",
+        $string,
+        make_duplicate_free($string)
+    );
+}
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Given a string, repeatedly remove adjacent duplicate letters until no
+# adjacent duplicates remain, even those produced by previous removals; if this
+# results in the removal of all letters, an empty string will be returned
+# Takes one argument:
+# * The string to process (e.g. "azxxzy")
+# Returns:
+# * The string with all duplicates removed as described above (e.g. "ay")
+################################################################################
+sub make_duplicate_free{
+    my $str = shift();
+
+    # Substitute an empty string (as opposed to
+    # a blank expression, to suppress 'uninitialized
+    # value' warnings) for all instances of two
+    # adjacent characters; keep doing so until no
+    # substitutions are made
+    while($str =~ s/(.)\1/""/ge){
+        ;;
+    }
+
+    return($str);
+
+}
+
+
+
diff --git a/challenge-340/mattneleigh/perl/ch-2.pl b/challenge-340/mattneleigh/perl/ch-2.pl
new file mode 100755
index 0000000000..6ac829b19a
--- /dev/null
+++ b/challenge-340/mattneleigh/perl/ch-2.pl
@@ -0,0 +1,88 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @strings = (
+    # Given cases
+    "The cat has 3 kittens 7 toys 10 beds",
+    "Alice bought 5 apples 2 oranges 9 bananas",
+    "I ran 1 mile 2 days 3 weeks 4 months",
+    "Bob has 10 cars 10 bikes",
+    "Zero is 0 one is 1 two is 2",
+
+    # Additional test cases
+    "There are no numbers here"
+);
+
+print("\n");
+foreach my $string (@strings){
+    my $rval = all_numbers_ascending($string);
+
+    printf(
+        "Input: \$str = '%s'\nOutput: %s\n\n",
+        $string,
+        $rval ?
+            "true"
+            :
+            defined($rval) ?
+                "false"
+                :
+                "no numbers present"
+    );
+}
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Given a string, determine whether positive integers therein appear in
+# ascending order from left to right
+# Takes one argument:
+# * The string to examine (e.g. "The cat has 3 kittens 7 toys 10 beds")
+# Returns:
+# * 0 if all the numbers in the string do NOT appear in ascending order
+# * 1 if all the numbers in the string appear in ascending order (as it would
+#   be in the case of the example above)
+# * undef if there are no numbers in the string
+################################################################################
+sub all_numbers_ascending{
+
+    my $previous = undef;
+
+    # Loop over only the numbers in the string
+    foreach my $number (grep(/^[0-9]+$/, split(" ", shift()))){
+        if(defined($previous)){
+            # There is a previously-defined number; bail
+            # if the current number is not greater than
+            # the previous one
+            return(0)
+                unless($number > $previous);
+        }
+
+        # Store this number to compare with the next
+        # one
+        $previous = $number
+    }
+
+    # Make sure we saw at least one number
+    return(undef)
+        unless(defined($previous));
+
+    # Got here- every number was more than the
+    # one that preceded it
+    return(1);
+
+}
+
+
+