Efficient Algorithm for String Concatenation with Overlap

Question

We need to combine 3 columns in a database by concatenation. However, the 3 columns may contain overlapping parts and the parts should not be duplicated. For example,

<

Answer 1

If you're doing it outside the database, try perl:

sub concat {
  my($x,$y) = @_;

  return $x if $y eq '';
  return $y if $x eq '';

  my($i) = length($x) < length($y) ?  length($x) : length($y);
  while($i > 0) {
      if( substr($x,-$i) eq substr($y,0,$i) )  {
          return $x . substr($y,$i);
      }
      $i--;
  }
  return $x . $y;
}

It's exactly the same algorithms as yours, I'm just curios if java or perl is faster ;-)