comment on

I keep thinking that this can be done using string-wise boolean operations, but I cannot see how?

Like this:

sub compatible {
    my( $l, $r ) = @_;

    # underscores are insignificant
    tr/_/\0/ for $l, $r;

    # cancel out identical values
    my $xor = $l ^ $r;

    # convert to bitmasks
    tr/\0/\377/c for $l, $r;

    my $mask = $l & $r;

    # masked chars must be identical
    return !1 if ( $xor & $mask ) =~ tr/\0//c;

    # and there may not be dupes of non-identical characters
    return 0 == grep {
        my $char = substr( $xor, $_, 1 );
        $char ne "\0" and index( $xor, $char, $_ + 1 ) != -1
    } 0 .. length( $xor ) - 1;
}
[download]

Test suite in the readmore.

#!/usr/bin/perl
use strict;
use warnings;

use Test::More;

my @testcase = (
    1 => [
        '_8__3__19',
        '48____7__',
    ],
    1 => [
        '_8__3__19',
        '48__3_7__',
    ],
    !1 => [
        '_8__3__19',
        '4_8___7__',
    ],
    !1 => [
        '____3__19',
        '3________',
    ],
    !1 => [
        '____3__19',
        '________8',
    ],
    !1 => [
        '_8__3__19',
        '48_____7_',
    ],
    !1 => [
        '__8_3__19',
        '84____7__',
    ],
);

plan tests => @testcase / 2;

while( my( $result, $strings ) = splice @testcase, 0, 2 ) {
    my $testname = join "\n" . ( " " x 18 ), (
        ( $result ? 'compatible' : 'conflicting' ) . ':',
        @$strings
    );
    is( compatible( @$strings ), $result, $testname );
}
[download]

Makeshifts last the longest.

In reply to Re: Comparison by position and value by Aristotle
in thread Comparison by position and value by BrowserUk

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, 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, 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:
	&		`&`
	<		`<`
	>		`>`
	[		`[`
	]		`]`

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.


Problems? Is your data what you think it is?
	PerlMonks