my @arr = qw(Apple Banana Tiger Lion Cat Turtle);
my $arr = join("|", @arr);

my $flag1 = ($arr =~ m/Apple|Turtle/) ? 1 : 0;
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That breaks as soon as the elements of @arr may contain the string used to join the arrays. Also, it roughly doubles the memory usage. Imagine a 2 GByte @arr on a machine with 4 GByte RAM.

Alexander