What type of work do you need to do on these times? The easiest thing to do is convert them all to seconds, and expand as needed (in my opinion). The biggest work would be reading in different formats, but that's not too hard if you know what they'll look like. The simplest input would be in the format "HH:MM:SS.ss".

# accepts the following forms:
#   HH:MM:SS.ss MM:SS.ss SS.ss HH:MM:SS MM:SS SS
sub time2sec {
  my ($s,$m,$h) = reverse(0, 0, split /:/, shift)
  return 3600*$h + 60*$m + $s;
}
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The reason for those leading 0's in the reverse() function are left as an exercise to the reader. :)

$_="goto+F.print+chop;\n=yhpaj";F1:eval