Re: Fast way to check if a sort was doen

[archfool]

Couldn't you make a flag variable and define a sort block? Concept:

$changed = 0;
my @array = sort {
  my $result = ($a cmp $b);
  $changed = 1  if $result==1; # Only set changed if $a > $b
  $result
} @oldarray;

[dewey]

I like this idea, but I couldn't get it to work.


my @oldarray = (0..9);

my @array = sort {
    my $result = ($a cmp $b);
    print "$result ";
    $result
    } @oldarray;

print "\n@array\n";

printed these results:

-1 -1 -1 -1 -1 -1 1 -1 1 1 1 -1 1 -1 1 1 1 1 1 
0 1 2 3 4 5 6 7 8 9

Without knowing exactly how the sorting algorithm is implemented, I don't see how we could reliably use this kind of method.

If OP wants to write a sorting function, they can include a flag... otherwise, this problem seems pretty solidly O(N) to me.