Have you considered what your 'rules' imply:

3. There could be multiple answers.
4. A Pattern may show up only once.
5. A Pattern may contain single character only

Every single char is by definition a pattern. So to is every combination of substrings. There will be quite a few answers. The number will be given by:

l + (l-1) + (l-2) + ..... ( l - (l - 1) ) + ( l - l )
where l = length of the string.

This is (l+(l**2))/2 for each and every string under your rules. BTW my substring/dictionary and best match hack returns this:

Best Matches:

6 occurrences of hello
4 occurrences of hi
4 occurrences of world
3 occurrences of book
3 occurrences of oh
2 occurrences of low
2 occurrences of pen

C:\>
[download]

Your rules are not specific enough to formulate an answer. How do you define what is part of a pattern. Is this "Igohellohellohellohi" a string that contains 3 'hello' or 4 'hi' or 6 'l'..... Perhaps concluding this was the real task?

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print