Have anybody crash on 3 test?
It's interesting, that my friend decided this problem and on tests with n>50 we have the same answer.

I had. You must add in your programm something like this:

 if(sum/9>2*n){
  printf("0");
  return 0;
 }

thanks. I just found my forgotten! my program cannot print 0 'zero' ( - -")

Why is this condition required? The recursive formula takes care of this.. Without this condition my code gets WA3.. And when I add it, it gets AC.. Could you plz give a test case where this condition is really required, where the DP formula fails..??

I don't think it's DP formula's fault
Perhaps when you are deleting leading zero, you haven't judge if the point is >= 0