One of the most positive things in codeforces is that we can see different approaches to solutions to the same problem.

For example to the problem 246D of today.

Approaches:

Suffix Automaton — 6626607

String Hashes — 6625476

Suffix Array — 6630083

Z-Algorithm — 6624439

KMP — 6627491

and many others, just we need find them. You have find another?