From b9d3e5b99b38fbbb0ca22fad76e3f548b34f97a1 Mon Sep 17 00:00:00 2001
From: Mohammad Sajid Anwar <mohammad.anwar@yahoo.com>
Date: Mon, 15 Sep 2025 23:35:06 +0100
Subject: - Updated and improved solution.

---
 challenge-339/mohammad-anwar/perl/ch-1.pl | 52 +++++++++++++------------------
 1 file changed, 22 insertions(+), 30 deletions(-)

diff --git a/challenge-339/mohammad-anwar/perl/ch-1.pl b/challenge-339/mohammad-anwar/perl/ch-1.pl
index 265579d0a8..c9bfb61ec3 100644
--- a/challenge-339/mohammad-anwar/perl/ch-1.pl
+++ b/challenge-339/mohammad-anwar/perl/ch-1.pl
@@ -6,37 +6,29 @@ use Test::More;
 use List::Util qw/max/;
 
 sub max_diff {
-    my @nums = @_;
-
-    # For 4 elements, there are only 3 possible pairings
-    if (@nums == 4) {
-        my ($a, $b, $c, $d) = @nums;
-        return max(
-            $a*$b - $c*$d,
-            $a*$c - $b*$d,
-            $a*$d - $b*$c,
-        );
-    }
-
-    # For larger arrays, we need to consider extreme values
-    my @s = sort {$a <=> $b} @nums;
-
-    # The maximum difference will likely come from:
-    # Option 1: (two largest) vs (two smallest)
-    # Option 2: (largest*smallest) vs (second largest*second smallest)
-    # Option 3: (largest*second smallest) vs (second largest*smallest)
-
-    my $opt1 = $s[-1]*$s[-2] -  $s[0]*$s[1];
-    my $opt2 = $s[-1]*$s[0]  - $s[-2]*$s[1];
-    my $opt3 = $s[-1]*$s[1]  - $s[-2]*$s[0];
-
-    return max($opt1, $opt2, $opt3);
+    my @n = @_;
+    my @pairs = map {
+        my $i = $_;
+        map { [$i, $_, $n[$i]*$n[$_]] } $i+1 .. $#n
+    } 0 .. $#n-1;
+
+    return max
+        grep { defined }
+        map {
+            my ($i,$j,$p1) = @$_;
+            map {
+                my ($k,$l,$p2) = @$_;
+                ($i==$k||$i==$l||$j==$k||$j==$l) ? () : $p1-$p2
+            } @pairs
+        } @pairs;
 }
 
-is(max_diff(5,9,3,4,6),   42);
-is(max_diff(1,-2,3,-4),   10);
-is(max_diff(-3,-1,-2,-4), 10);
-is(max_diff(10,2,0,5,1),  50);
-is(max_diff(7,8,9,10,10), 44);
+is(max_diff(5,9,3,4,6),       42);
+is(max_diff(1,-2,3,-4),       10);
+is(max_diff(-3,-1,-2,-4),     10);
+is(max_diff(10,2,0,5,1),      50);
+is(max_diff(7,8,9,10,10),     44);
+is(max_diff(-1,0,1,2,3,4,5),  23);
+is(max_diff(-10,0,1,2,3,4,5), 62);
 
 done_testing;
-- 
cgit