我的作法是每输入一个Relation，就做一次拓扑排序，如果排序输出的个数少于n，就说明出现的回环，结果为“Inconsistency"，否则，如果所构成的网里是否只有一个点的入度为0和只有一个点的出度也为0，且改网是连通图，则结果是”Sorted sequence can be determined.“，否则继续，知道判断完最后一个Relation。

测试数据和运行结果如下：
4 4
A<B
C<D
B<C
D<A
4 6
A<B
A<C
B<C
A<A
C<D
B<D
4 6
A<C
B<C
B<A
C<D
B<D
D<A
4 3
A<B
C<D
D<C
4 3
A<B
C<B
B<D
5 5
A<B
B<D
C<B
D<E
E<D
3 2
A<B
B<A
26 1
A<Z
4 2
A<B
C<D
2 2
A<A
A<B
2 2
A<B
B<A
0 0

Sorted sequence determined after 3 relations: ABCD.
Inconsistency found after 4 relations.
Sorted sequence determined after 4 relations: BACD.
Inconsistency found after 3 relations.
Sorted sequence cannot be determined.
Inconsistency found after 5 relations.
Inconsistency found after 2 relations.
Sorted sequence cannot be determined.
Sorted sequence cannot be determined.
Inconsistency found after 1 relations.
Sorted sequence determined after 1 relations: AB.

• Re:这题的数据会不会是出了问题？ (11) kingway 2007-01-25 14:00:25