var
  i, j, k, tot, ii: longint;
  n1, n2: longint;
  b: array[0..501] of boolean;
  a: array[0..501,0..501] of boolean;
  rec: array[0..501] of longint;
  ans: longint;
  x, y: longint;

function dfs(x: longint): boolean;
var
  i, j, k: longint;
begin
  for i := 1 to n2 do if (not b[i]) and (a[x,i]) then begin
    b[i] := true;
    if (rec[i]=0) or (dfs(rec[i])) then begin
      rec[i] := x;
      exit(true);
    end;
  end;
  exit(false);
end;
  
begin
  assign(input,'d:\01.in');
  reset(input);
  assign(output,'d:\01.out');
  rewrite(output);
  readln(tot);
  for ii := 1 to tot do begin
    readln(n1,n2);
    fillchar(rec,sizeof(rec),0);
    fillchar(a,sizeof(a),false);
    for i := 1 to n1 do begin
      read(x);
      for j := 1 to x do begin
        read(y);
        a[x,y] := true;
        //a[y,x] := true;
      end;
      readln;
    end;
    ans := 0;
    for i := 1 to n1 do begin
      fillchar(b,sizeof(b),false);
      if dfs(i) then inc(ans);
    end;
    if ans=n1 then writeln('YES') else writeln('NO');
  end;
  close(input);
  close(output);
end.
求数据求数据~~~

• 显然会wa (61) xqzxqz 2011-08-15 09:59:50
• 不过你改了，还是错了，我不知道原因，我写的也错了 (0) xqzxqz 2011-08-15 10:01:36