Obsessive String The first part of substring search(using KMP ) is clear. I was going through the editorial but the DP state is unclear to me. Is it some standard counting technique. If yes could anyone provide similar problem links ?

I was trying to solve this problem on UVA : https://uva.onlinejudge.org/index.php?option=onlinejudge&Itemid=8&page=show_problem&problem=3133 I have solved a similar problem with smaller constraint using dp+bitmask. Can anyone suggest some approach or link some similar problems.