From a01357c96a9bc6f4425e77a5254419e4f603a7b9 Mon Sep 17 00:00:00 2001
From: Bob Lied <boblied+github@gmail.com>
Date: Thu, 2 Nov 2023 19:00:44 -0500
Subject: Optimization to end loop early once difference can't be achieved

---
 challenge-241/bob-lied/perl/ch-1.pl | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/challenge-241/bob-lied/perl/ch-1.pl b/challenge-241/bob-lied/perl/ch-1.pl
index 28954dc13b..efb05edce9 100644
--- a/challenge-241/bob-lied/perl/ch-1.pl
+++ b/challenge-241/bob-lied/perl/ch-1.pl
@@ -46,10 +46,17 @@ sub triplet($diff, @nums)
     {
         for ( my $j = $i+1; $j <= $#nums-1; $j++ )
         {
-            next unless $nums[$j] - $nums[$i] == $diff;
+            my $dj = $nums[$j] - $nums[$i];
+
+            # Input is sorted, so stop once the difference is too big.
+            last if $dj > $diff;
+            next unless $dj == $diff;
+
             for ( my $k = $j+1; $k <= $#nums ; $k++ )
             {
-                if ( $nums[$k] - $nums[$j] == $diff )
+                my $dk = $nums[$k] - $nums[$j];
+                last if $dk > $diff;
+                if ( $dk == $diff )
                 {
                     $count++;
                     push @show, [ $i, $j, $k ] if $Verbose;
-- 
cgit