Try to update to more modern perl

AoC/2024/day_1/day_1.pl

@@ -2,19 +2,19 @@
 use v5.40;
 
 sub day1_1( $filename ) {
-    open(my $FH, '<', $filename) or die $!;
+    open my $fh, '<', $filename;
 
     my @list1;
     my @list2;
 
     my $counter = 0;
-    while(<$FH>) {
-        my @data = split(" ", $_);
+    while(my $line = readline $fh) {
+        my @data = split " ", $line;
         if (@data == 2) {
-            push(@list1, $data[0]);
-            push(@list2, $data[1]);
+            push @list1, $data[0];
+            push @list2, $data[1];
         } else {
-            print("More than two data points found at: $counter\n");
+            print "More than two data points found at: $counter\n";
             return -1;
         }
         $counter++;
@@ -23,30 +23,21 @@ sub day1_1( $filename ) {
     @list1 = sort @list1;
     @list2 = sort @list2;
 
-    if ($#list1 != $#list2) {
+    if (@list1 != @list2) {
         print("indices don't match\n");
         return -1;
     }
 
     my $total = 0;
-    for( my $i = 0; $i<=$#list1; $i++) {
+    foreach my $i ( 0 .. $#list1) {
         $total += abs($list1[$i] - $list2[$i]);
     }
 
-    close($FH);
+    close $fh;
 
     return $total;
 }
 
-sub round( $num ) {
-    my $base = int($num);
-    if($num - $base >= 0.5) {
-        $base++;
-    }
-
-    return $base
-}
-
 sub find_count($item, $is_sorted, @list) {
     if($is_sorted != 1) {
         @list = sort @list;