example N = 11, M = 3;

123
456
789
ab

the cell "3" can reach from the cell "9",
pushing an arrow key only once?
I mean "arrow down"?

No! You can't reach "3" from "9" pushing only one key.

Why not?

Because, there is nothing about this kind of actions in the task! From the key "9" you can only reach "1", "8", "6".

there is not such words in statement.
statement of the problem is not full.

There are discribed all avaliable actions in statement and nothing more. So I can't agree with you))

You said that we can reach "1" from "9". How? If we push
"Right" we'll reach "a", I think...

Push "Left" and you'll reach "9" from "1"))

No, sorry, my mistake... "9" from "3"!
You said that we can reach "9" from "3".
I just pushed wrong digit...

I didn't say it. You can reach "3" from "9" by pushing 2 keys!)


Edited by author 30.04.2007 22:31

1. You said
Because, there is nothing about this kind of actions in the task! From the key "9" you can only reach "1", "8", "6".

So, how we can reach "1" from "9"?

2.Later you said
"Push "Left" and you'll reach "9" from "1"))"
We'll reach "b" by pushing Left.

Edited by author 01.05.2007 00:11

Oh! I got it!)) I meant the field
1 2 3
4 5 6
7 8 9
So you are right!) Sorry!)

It's not clear from problem statement because meaning of "moving cursor up" and "moving cursor down" depends on topology. We'd assume default flat topology with boundaries, but special rules for LEFT/RIGHT makes us thinking that there are similar rules for UP/DOWN. At least moving down from row Y-1 to empty cell in row Y could result in stop at the last character.

Edited by author 02.08.2008 13:07

Mean = 1.55
2 1 2
1 0 1
2 1 2
3 2