> 从大到小一个个放，试想现在该放第i个，放两边就增加一对说话者，放中间就增加两个说话者，所以f[i,j]:=(f[i-1,j-2]*(i-2)+f[i-1,j-1]<<1)mod 9937;
> 
> 
> Problem: 3934  User: lydliyudong 
> Memory: 924K  Time: 0MS 
> Code Length: 299B
> Language: Pascal  Result: Accepted 
> 
> 
> 
> var
>  f:array[0..80,-1..157]of longint;
>  n,m,i,j:longint;
> begin
>  f[1,0]:=1;
>  for i:=2 to 80 do
>   for j:=i-1 to i<<1-3 do
>    f[i,j]:=(f[i-1,j-2]*(i-2)+f[i-1,j-1]<<1)mod 9937;
>  read(n,m);
>  while n+m<>0 do
>   begin
>    if m>157 then writeln(0) else writeln(f[n,m]);
>    read(n,m);
>   end;
> end.