I don't think that there is a good short way to state it.

Perhaps the best way is to be verbose as in: 

my @available;
if ( $door[ $choice ] eq 'car' ) {
  # Can't beat him yet
  @available = grep { $choice != $_ } 0 .. 2;
}
else {
  # Make him lose!
  @available = grep { $doors[ $_ ] eq 'car' } 0 .. 2;
}

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In reply to Re^9: Marilyn Vos Savant's Monty Hall problem by tilly
in thread Marilyn Vos Savant's Monty Hall problem by mutated

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