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.

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