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

for my $given ( "(A & B)'",
                "((A & B)' | (A & C & (A & B & D)'))",
                "((A | B)' & (C | (D & (E & F)))')'",
                "((A & B)' | (A & C & (A & B & D | (A & (B' & D)')'))"
              ) {
    my @left;
    my $calc = $given;
    my $last;
    for my $pos (0 .. length($given) - 1) {
        my $current = substr $given, $pos, 1;
        push @left, $pos if '(' eq $current;
        $last = pop @left if ')' eq $current;
        if ("'" eq $current) {
            substr $calc, $pos, 1, q();

            if (')' eq substr $calc, $pos - 1, 1) { # Negated parentheses.
                substr $calc, $last, 0, '!';

            } else {                                # Negated literal.
                substr $calc, $pos - 1, 0, '!';
            }
        }
    }
    print "Given: $given\n";
    print "Calculated: $calc\n";
}