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

my @set = qw(one bright day in the middle of the night);
my %pos;

# Preprocess @set
{
    no warnings 'uninitialized';
    vec( $pos{ ord( $set[ $_ ] ) }, $_, 1 ) = 1 for 0 .. $#set;
}

while ( my $val = <DATA> ) {
    chomp $val;
    my $bitstr = $pos{ ord( $val ) } or next;
    my $i = length( $bitstr ) * 8 - 1;
    while ( $i-- ) {
        print "$val\n" and last if vec($bitstr, $i, 1) && $val eq $set[ $i ];
    }
}
__DATA__
one
two
buckle
my
shoe
the
cat
in
the
hat