in reply to Re: Bidirectional lookup algorithm? (Updated: further info.)
in thread Bidirectional lookup algorithm? (Updated: further info.)

The integers are 64-bits. I do not know what they really look like, but there is clear danger of ending up with a sparse array growing to be much much larger than the hash.
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Re^3: Bidirectional lookup algorithm? (Updated: further info.)
by shmem (Chancellor) on Jan 05, 2015 at 22:34 UTC

    Right you are. 

    qwurx [shmem] ~/comp/perl/tmp > perl -le '@a = 2**64; for(1..29){$a[2*
+*$_]=$_}print `ps -o vsz= -p $$`'
Out of memory!

    [download]

    Having 8 GB RAM. 2**28 doesn't die.

    perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'
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