It's obvious we calculate recurrence with Matrix.But in the base Matrix,I first used -1,then I got WA#3,while I replaced it with m-1,I got AC.Who can explain it to me?

Edited by author 07.02.2015 18:44

I think you mean first used +1, not -1? -1 makes strange recurrence

If you mean +1, then makes Fibonacci sequence. But problem not Fibonacci, although similar idea.

When use m - 1 to replace +1, makes problem's recurrence