4 memory or 30000 memory ?

I have WA 28 Also.
First 27 test I have passed with N=3 using Dejkstra.
But N==4 means very many possible states 27*27*27*27*4*50
and unprocessing.

optimal program use 4 or less cells

It's evident that using 5 cells we will have better solution for rather long strings, but jury's programm can't
work properly in this situation. Their hight level is 4 when they garantee right answer. I easy found Dejkstra's
solution for N=3. But for N=4 I tried DP,BFS with absolutely
bad characteristics. If solution depend on unproven statements which help diminish cardinality of set of possible states then it is unfair.

It's possible to work with DP over 27*27*27*4*50 states for 4 modifiable cells. Yes, this uses some interesting assumption but it is provable.

P.S: got AC

Edited by author 14.07.2008 02:52

Edited by author 14.07.2008 03:54

Could you tell me what's your assumption?
I think DP should be 27^4 * 4 * 50,
and I assume that we just need modify 3 cells...
so I got wa#28~
could anybody help me?
sorry for my poor English.

I think you can assume that cell with position 0 <= i < 4  already have needed char.