new file: challenge-137/mattneleigh/perl/ch-1.pl

	new file:   challenge-137/mattneleigh/perl/ch-2.pl

2 files changed, 205 insertions, 0 deletions

diff --git a/challenge-137/mattneleigh/perl/ch-1.pl b/challenge-137/mattneleigh/perl/ch-1.pl
new file mode 100755
index 0000000000..a5c33edecc
--- /dev/null
+++ b/challenge-137/mattneleigh/perl/ch-1.pl
@@ -0,0 +1,99 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @years = ();
+
+print("\n");
+for(1900 .. 2100){
+    # See if this year is a long year...
+    if(weeks_in_year($_) == 53){
+        # Store it if it is...
+        push(@years, $_);
+        if($#years == 4){
+            # There are five years stored- print
+            # them out and flush the year-buffer
+            print(join(", ", @years), "\n");
+            @years = ();
+        }
+    }
+}
+if(@years){
+    # Some unprinted years remain; print
+    # them out too
+    print(join(", ", @years), "\n");
+}
+print("\n");
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Determine how many weeks there are in a given year
+# Takes one argument:
+# * The year (e.g. 1937)
+# Returns:
+# * The number of weeks in the year, which will be either 52 or 53
+################################################################################
+sub weeks_in_year{
+    my $year = shift();
+
+    # Did this year end on Thursday or the
+    # previous year end on Wednesday?
+    if(
+        (new_years_eve_weekday($year) == 4)
+        ||
+        (new_years_eve_weekday($year - 1) == 3)
+    ){
+        # Yes...
+        return(53);
+    } else{
+        # No...
+        return(52);
+    }
+    
+}
+
+
+
+################################################################################
+# Determine on which day of the week December 31 falls in a given year
+# Takes one argument:
+# * The year (e.g. 1937)
+# Returns:
+# * The day of the week on which December 31 occurs in the given year, ranging
+#   from 0 (Sunday) to 6 (Saturday)
+################################################################################
+sub new_years_eve_weekday{
+    use POSIX;
+
+    my $year = shift();
+
+    return(
+        (
+            $year
+            +
+            floor($year / 4)
+            -
+            floor($year / 100)
+            +
+            floor($year / 400)
+        )
+        %
+        7
+    );
+
+}
+
+
+
diff --git a/challenge-137/mattneleigh/perl/ch-2.pl b/challenge-137/mattneleigh/perl/ch-2.pl
new file mode 100755
index 0000000000..9a08119cd2
--- /dev/null
+++ b/challenge-137/mattneleigh/perl/ch-2.pl
@@ -0,0 +1,106 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @numbers = (
+    # Given cases
+    56, 57, 59,
+
+    # Additional test cases
+    1500, 196
+);
+my $number;
+my $iterations = 0;
+
+print("\n");
+foreach $number (@numbers){
+    my $rval = is_lychrel_number($number, \$iterations);
+
+    print("Input: \$n = $number\n");
+    print("Output: ", defined($rval) ? $rval : "Invalid input", "\n");
+    print(
+        "After $iterations iteration",
+        ($iterations == 1 ? "" : "s"),
+        ", we found ",
+        defined($rval)
+        ?
+        ($rval ? "no palindromes" : "a palindrome")
+        :
+        "that our input was not valid",
+        ".\n\n"
+    );
+    $iterations = 0;
+}
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Determine whether a number appears to be a Lychrel number- a natural number
+# that cannot form a palindrome through the iterative process of repeatedly
+# reversing its digits and adding the resulting numbers.  To limit the use of
+# computing resources, this function will declare an input value to be a
+# probable Lychrel number if the running total exceeds 10000000 or more than
+# 500 iterations have passed.  Input values are also restricted to those
+# between 10 and 1000, inclusive.
+# Takes two arguments:
+# * A number N to evaluate
+# * Optionally, a ref to a scalar that may be populated with the number of
+#   iterations required to determine whether N appeared to be a Lychrel number
+# Returns on success:
+# * 0 if N does not appear to be a Lychrel number
+# * 1 if N appears to be a Lychrel number
+# Returns on error:
+# * undef if N is less than 10 or more than 1000
+################################################################################
+sub is_lychrel_number{
+    my $n = int(shift());
+    my $iter = shift();
+
+    $$iter = 0 if(defined($iter));
+
+    # Establish a range of valid inputs
+    return(undef) unless(($n > 9) && ($n < 1001));
+
+    my $i = 0;
+    my $reversed = 0;
+
+    while($i <= 500){
+        # Swap digits around and compare...
+        $reversed = reverse(split("", $n));
+        if($reversed == $n){
+            # Found a palindrome- this is not a
+            # Lychrel number
+            $$iter = $i if(defined($iter));
+            return(0);
+        }
+
+        # Add the reversed number to the total,
+        # and bail if the number is too large
+        $n += $reversed;
+        last if($n >= 10000000);
+
+        $i++;
+    }
+
+    # If we got here, either the total got
+    # too large, or we ran out of
+    # iterations; we'll assume this is a
+    # Lychrel number
+    $$iter = $i if(defined($iter));
+    return(1);
+
+}
+
+
+