getting the job done in less than a half of second

While this is certainly a neat approach, and much better memory-wise (as long as you can keep the maximum possible number within limits...), it isn't actually faster than using a hash.  The slightly modified code (to make it comparable with the hash version I suggested) takes about the same running time on my system. For example, with 1000_000 values to look up: 

$ time ./757954_bytevector.pl >out

real    0m4.421s
user    0m4.368s
sys     0m0.048s

----------

#!/usr/bin/perl

# create file with numbers to look up
open (my $fh, ">", "in.txt") || die "$!";
for (1..1000000) {
    print $fh int rand 1e6, "\n";
}
close $fh;

my $ids = 1000000;  # last id
my $bin=0;
substr($bin,$_,1,pack ("c",0)) for (0..$ids);

# Create the index
for (1..400000) {
    my $id = int rand 1e6;
    substr($bin, $id,1,pack ("c",1));
}

# Search $ids
open my $fh2, "<", "in.txt" or die $!;
while (<$fh2>){
    my ($num) = m/^(\d+)/;
    print "$num, " if ((unpack "c",substr ($bin,$num,1)) == 1);
}

[download]

In reply to Re^2: searching through data by almut
in thread searching through data by baxy77bax

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.