Problem: http://www.spoj.com/problems/ADACLEAN/ Solution: http://ideone.com/TracEP Verdict: Wrong Answer

I just learned about hashing and tried to solve this problem using the technique. My idea is I will pre-process _hash array with the hash values and afterwards I will just extract hashes of all the k-length strings and keep that in a map. Afterwards, I just output the size of the map. Any help to identify my mistake is really appreciated.