Yet another, more difficult palindrome problem

Question

Hi guys,
I also have a Palindrome problem! For this problem, we are given a string and we have to print out all the possible palindromes of all the subsets of this string, in order.
For example, given "ab", the set of subsets would be {a, ab, b, ba} and we'd have to print out:
a
aa
aba
abba
b
baab
bab
bb
Each substring has 2 palindromes (i.e. abc has palindromes abcba and abccba).
I know we can easily generate all the substrings and all the palindromes and then just sort it. However, for a string of 8 characters, we're required to print out all the palindromes in 3.2 seconds! (If the 8 characters are unique, that's over 200,000 lines!).
Any ideas on how to go about this? Is there an elegant recursive solution for this? Would using an ArrayList slow down my program? Is there a faster way to print things?
Thanks a bunch!!!

Answer 1

Hi,
I've actually finished writing it. I've been trying
to speed it up for 2 days now. I've managed to tweak
it from 13 seconds to 7 seconds, but it's still too
slow (i need it to be faster than 3.2 seconds).
Thanks!Who are you? Are you val018?
I have to be a bit stupid, but I don't understand the rules. You say:
given "ab", the set of subsets would be {a, ab, b, ba} O, that I understand, and then you show the example output.
a
aa <-- How do you construct this from the subsets shown?
aba
abba
b
baab
bab
bbThat is. Are you allowed to use the same subset more than once? In that case you have an infinitive result set:
a
aa
aaa
aaaa
etc..
/Kaj