BCDIV - Chia nhóm
Tác giả: flashmt
Ngôn ngữ: Pascal
var n,k:byte;
t,p:longint;
a:array[1..25,1..25] of int64;
procedure init;
var i,j:longint;
begin
fillchar(a,sizeof(a),0);
for i:=1 to 25 do
begin
a[i,1]:=1; a[i,i]:=1;
for j:=2 to i-1 do
a[i,j]:=a[i-1,j]*j+a[i-1,j-1];
end;
end;
begin
init;
readln(t);
for p:=1 to t do
begin
readln(n,k);
writeln(a[n,k]);
end;
end.