From f5ffc3743a0f12f5998564b9b1fb621e4ec1b689 Mon Sep 17 00:00:00 2001
From: Matthew Neleigh <matthew.neleigh@gmail.com>
Date: Mon, 11 Apr 2022 04:16:02 -0400
Subject: 	new file:   challenge-160/mattneleigh/perl/ch-1.pl 	new
 file:   challenge-160/mattneleigh/perl/ch-2.pl

---
 challenge-160/mattneleigh/perl/ch-1.pl | 62 +++++++++++++++++++++++
 challenge-160/mattneleigh/perl/ch-2.pl | 89 ++++++++++++++++++++++++++++++++++
 2 files changed, 151 insertions(+)
 create mode 100755 challenge-160/mattneleigh/perl/ch-1.pl
 create mode 100755 challenge-160/mattneleigh/perl/ch-2.pl

diff --git a/challenge-160/mattneleigh/perl/ch-1.pl b/challenge-160/mattneleigh/perl/ch-1.pl
new file mode 100755
index 0000000000..a6d2212f24
--- /dev/null
+++ b/challenge-160/mattneleigh/perl/ch-1.pl
@@ -0,0 +1,62 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @table = (
+    [ "zero",  4 ],
+    [ "one",   3 ],
+    [ "two",   3 ],
+    [ "three", 5 ],
+    [ "four",  4 ],
+    [ "five",  4 ],
+    [ "six",   3 ],
+    [ "seven", 5 ],
+    [ "eight", 5 ],
+    [ "nine",  4 ]
+);
+my @numbers = ( 5, 7, 6 );
+my $number;
+
+print("\n");
+foreach $number (@numbers){
+    unless(($number > -1) && ($number < 10)){
+        warn("Invalid number $number\n\n");
+        next;
+    }
+
+    my $string = "";
+
+    print("Input: \$n = ", $number, "\n");
+    print("Output: ");
+    until($number == 4){
+        # This number isn't four; add its count details
+        # and advance to the next number
+        $string .= 
+            $table[$number][0] .
+            " is " .
+            $table[$table[$number][1]][0] .
+            ", ";
+        $number = $table[$number][1];
+    }
+    
+    # We must have hit four, so add the magical
+    # sentiment, upper-case what's first, and
+    # output...
+    $string .= "four is magic.";
+    $string =~ s/^(.)/uc($1)/e;
+    print($string, "\n\n");
+}
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
diff --git a/challenge-160/mattneleigh/perl/ch-2.pl b/challenge-160/mattneleigh/perl/ch-2.pl
new file mode 100755
index 0000000000..11d5868909
--- /dev/null
+++ b/challenge-160/mattneleigh/perl/ch-2.pl
@@ -0,0 +1,89 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+use English;
+
+################################################################################
+# Begin main execution
+################################################################################
+
+my @arrays = (
+    [1, 3, 5, 7, 9],
+    [1, 2, 3, 4, 5],
+    [2, 4, 2]
+);
+my $array;
+
+print("\n");
+foreach $array (@arrays){
+    my $rval = calculate_equilibrium_index(@{$array});
+
+    printf(
+        "Input: \@n = (%s)\nOutput: %s\n\n",
+        join(", ", @{$array}),
+        (
+            $rval < 0
+            ?
+            $rval . " as no Equilibrium Index could be found."
+            :
+            $rval
+        )
+    );
+}
+
+exit(0);
+################################################################################
+# End main execution; subroutines follow
+################################################################################
+
+
+
+################################################################################
+# Calculate the Equilibrium Index of an array of numbers- that is to say, the
+# index at which the sum of the values behind (but not including) the index is
+# equal to the sum of the values ahead (but not including) the index.  There
+# must be at least three elements in the array for this calculation to take
+# place.
+# Takes one argument:
+# * The list to examine
+# Returns:
+# * The Equilibrium Index, or -1 if no Equilibrium Index can be found, which
+#   includes cases where the array contains fewer than three elements
+################################################################################
+sub calculate_equilibrium_index{
+
+    # Can't have an equilibrium index if there
+    # aren't at least three elements
+    return(-1)
+        if(scalar(@ARG) < 3);
+
+    my $fore = 0;
+    my $aft = $ARG[0];
+    my $i = 1;
+
+    # Compute the fore total
+    for(2 .. $#ARG){
+        $fore += $ARG[$_];
+    }
+    
+    # Loop from 1 to ($#ARG - 1)
+    while($i < $#ARG){
+        if($aft == $fore){
+            # Found an equilibrium index- return it
+            return($i);
+        }
+
+        # Advance the index, adjusting the fore and
+        # aft totals
+        $aft += $ARG[$i];
+        $fore -= $ARG[++$i];
+    }
+
+    # No equilibrium index found
+    return(-1);
+
+}
+
+
+
-- 
cgit