Edmund von der Burg (ecclestoad.co.uk)has written a simple sudoku solver. The solver processes one sudoku and then dies.

To be able to handle a list of sudokus as input I adhoc replaced the "die" command by "warn".

That had the effect that the execution time for the 5 sudokos of the example increased from 82 s (for die) to 717 s.

use integer;
my $start = time;
while(<DATA>){
  if(/#----END----#/){ 
    my $duration = time - $start;
    die "Execution time: $duration s\n";
  }
  @A = split //,; &R; 
}
sub R { 
    for $i ( 0 .. 80 ) { 
        next if $A[$i];
        my %t = map {
          $_/9==$i/9||$_%9==$i%9||$_/27==$i/27&&$_%9/3==$i%9/3?$A[$_]:
+0=>1
        } 0 .. 80; 
        R($A[$i]=$_) for grep{!$t{$_}} 1 .. 9;
        return $A[$i] = 0;
    }   
    $sum=0; for(@A){$sum+=$_} print" $sum\n";
    warn @A;          # Execution time = 717 s
#    die @A;          # Execution time 31 + 31 + 14 + 1 + 5 = 82 s
}
__DATA__
1204003003000100500060001007000900000406030000030020005000807000070000
+05000000098
0000000390000010050030508000080900060700020001004000000090800500200006
+00400700000
1203000043500001000040000000054002006000700000000080900031005000000090
+70000060008
0030000004000800360080001000400600730009000000000020050040700686000000
+00700600500
8000000000036000000700902000500070000000457000001000300010000680085000
+10090000400
#----END----# 
1284653793742198569568371427651984232496735818135429675923867144879216
+35631754298
7518462398923714656432598712381975469745623181654389273196847525279136
+84486725193
1263957843598471628746219539854162376319728452475386917631845294182593
+76592763418
1234567894571892369683271542495618735769384128317426953142759686958143
+27782693541
8127536499436821756754912831542378963698457212871695345219743684385269
+17796318452
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