Re^2: Canadian Cryptography Contest

[tadman]

Then, of course, you would do the following:

for(1..1e6){$s+=$_ for/./g};print$s

Unfortunately, map seems to choke on 1e6 entries.

[tilly]

perl -e'map$\+=$_,/./g for 1..1e6;print'

also works. OTOH before this is done running you should be able to reason out why the answer is 27,000,001. (Big hint. The 1 is the contribution from the 7'th digit.) As for map chocking, if you are on any Perl before 5.6.1, the many for one map shows quadratic performance, so it will indeed choke and remain choked for a good while on a million entries.

[tadman]

map choked completely, by using massive amounts of memory.

This is perl, v5.6.1 built for i686-linux

Must be one of those things.

[tilly]

Hrm.

Possible. After all you are taking a list of a million, turning that into a list of about 6 million things, then allocating 6 million scalars. If each scalar takes 32 bytes, that is 192 MB just for the scalars, not even counting the space taken by the stack...

With 5.6.0 and earlier you would have had the same potential problem, but would likely get bored before taking enough hours to get there.

[Aristotle]

Ok, explain. Try as I might I can't figure out what you're trying to get at.

Makeshifts last the longest.