Assuming that the description a string of 0s and 1s of some length (lets say "1010101011") means string of bytes where each byte is either '0' or '1', and that the list of indices is subject to change with each call, then I'd try something like this. 

sub buk2{
    my $s = shift;
    substr $s, $_-1, 1 eq substr $s, $_, 1 and return for @_;
    return 1;
}

[download]

It fails quickly if possible, and avoids creating lots of intermediate scalars or arrays.

If the '1's and '0's are bits encoded in a numeric value and the list of indices are reused, then zaxo's method is probably much quicker.

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

In reply to Re: fast bit twiddling by BrowserUk
in thread fast bit twiddling by spurperl

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