Re^2: Find Length Of Longest Ascending/Descending Sequence

[wind]

As far as I can tell, when using a purely regex solution, you pretty much have to keep the scanning for ascending and descending sequences separated. Otherwise overlapping sequences will be missed:

123xxxx56543

Capturing in one go will return qw(123 56 543) instead of qw(123 56 6543);

my $asc = join '|', map {"$_(?=".(($_+1)%10).")"} (0..9);
my $dsc = join '|', map {"$_(?=".(($_+9)%10).")"} (0..9);

while (<DATA>) {
    my $longest = max map length, /((?:$asc)+)/g, /((?:$dsc)+)/g;
    print "$longest\n";
}

Update: This was in reference to your last solution, as previous ones did take this into account.

[ikegami]

Capturing in one go will return qw(123 56 543) instead of qw(123 56 6543);

Which isn't a problem when you just want the length. The result is 1 more than the length of the longest capture. That's why I increment $longest at the end.

...or rather, that's why I was planning on incrementing $longest at the end. Fixed.

[wind]

The result is 1 more than the length of the longest capture.

Why? If the full string is "123", then the result should be 3. If it's "21234", then the result should be 4. Still need to take overlaps into account even if you just want the length.

Btw, still have the typo in your last bit of code where you use min instead of max.

my $longest =
   min
   map length,

[ikegami]

You don't seen to have read my code closely enough. Specifically, you missed that I capture one short of the whole sequence.

Why? If the full string is "123", then the result should be 3.

For "123", "12" is captured and length("12") + 1 is 3.

If it's "21234", then the result should be 4.

For "21234", "123" is captured and length("123") + 1 is 4.

Still need to take overlaps into account even if you just want the length.

True, but I avoided needing to capture the same digit twice, and thus I avoided the need to visit the string twice.

you use min instead of max.

Thanks, fixed.