/CH - Chỉnh Hợp KL

<Problem>

http://ntucoder.net/Problem/Details/3379
              Uses Crt;
        Var d,x:array[1..10000] of longint;
            n,k:longint;
        Procedure Ghi;
        var i:longint;
        begin
            for i:=1 to k do write(x[i],' '); writeln;
        end;
        Procedure Doit(i:longint);
        var j:longint;
        begin
            for j:=1 to n do
            if d[j]=0 then begin //Cac chu so khong duoc giong nhau
                d[j]:=1; // Khi tien len ta danh dau cac so da xet
                x[i]:=j;
                if i=k then ghi else Doit(i+1);
                d[j]:=0; // Khi quay lui ta bo danh dau so j
            end;
        end;
        Begin
            readln(n,k);
            doit(1);
        End.