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At lot more efficient by linearizing a O(N^2) function in

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check_safety. I think this can be further optimized by using
a temporary hash. Anyway, on a directory with 5327 files swapping to
file names had this effect:

time mvwrap.old -n
mvwrap.old -n  183.40s user 0.11s system 91% cpu 3:20.83 total

became:

time mvwrap -n
mvwrap -n  29.03s user 0.15s system 78% cpu 36.946 total

Which still takes too long, but is a lot better. ;)
This commit is contained in:
Ward Wouts 2002-02-04 21:59:53 +00:00
parent ad85d0295d
commit 26c1f324d4
1 changed files with 10 additions and 4 deletions
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10
mvwrap/mvwrap
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@ -170,11 +170,16 @@ sub check_unique (@target_list){
# Returns an array of unsafe line numbers
sub check_safety {
my ($from, $to) = @_;
my ($i, $j, @danger, @unique, %seen);
my ($i, $j, @changed, @danger, @unique, %seen);
my ($a, $b);
for ($i=0; $i < scalar(@$from); $i++){
for ( $j=0; $j < scalar(@$to); $j++ ) {
$a = $from->[$i]; chomp($a);
$b = $to->[$i]; chomp($b);
push @changed, $i if ($a ne $b);
}
foreach $i (@changed) {
$a = $from->[$i]; chomp($a);
for ($j=0; $j < scalar(@$to); $j++){
$b = $to->[$j]; chomp($b);
if (($a eq $b) && ($i != $j)) {
push @danger, $i;
@ -182,6 +187,7 @@ sub check_safety {
}
}
}
%seen = ();
@unique = grep { ! $seen{$_} ++ } @danger;
return @unique;