🚀 go-pugleaf

In article <4gsn1d$ia@epervier.CC.UMontreal.CA> pigeons@JSP.UMontreal.CA (PIGEON Steven) writes:

>Harlan Messinger (gusty@clark.net) wrote:
>: void getLastFactorialDigits(int results[], // assume sufficient space
>:                                            // was preallocated (n+1 bytes)
>:                               int n) {
>: 
>:       results[0] = 1;
>:       results[1] = 1;
>:       for (int i = 2; i <= n; ++i) {
>:               results[i] = results[i - 1] * i;
>:               while (results[i] % 10 == 0)
>:                       results[i] /= 10;
>:               results[i] = results[i] % 10;
>:       }
>:       return;
>: }


>Ah a! In PASCAL!!! :-) This is a Pascal group!



> function zerofacto(n:integer):integer;
> var s,j,i:longint;
>  begin
>   s:=1;
>   j:=1;
>   i:=0;

>   while (j<=n) do
>    begin
>     s:=s*j;
>     while ( (s>10) and (s mod 10=0)) do
>      begin
>       s:=s div 10;
>       inc(i);
>      end;
>     s:=s mod 10;
>     inc(j);
>    end;
>    zerofacto:=s mod 10;
>  end;



Since there are less than 69 factorials that can be represented in most real 
number systems, this would be a great place for a table-lookup.  Calculate 
them once and store them in a constant array.