If we hash either, a or b, we always will lose something
Take another look at Abigail-II's solution and note that the question specifically states that the order of the results is unimportant. 
#!/usr/bin/perl -wT
use strict;

my @a_array = qw( a c f r f z t  );
my @b_array = qw( e c s f r f) ;

my %b_hash;
$b_hash {$_} ++ for @b_array;
my @c_array = map {($_) x ($b_hash {$_} || 0)} @a_array;

print "@c_array\n";

__END__
c f f r f f

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-Blake

In reply to Re2: (OT) Interview questions -- your response? by blakem
in thread (OT) Interview questions -- your response? by Ovid

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