A题
http://jgjwc.bjtu.edu.cn:8080/bjtumcm/jforum/jforum.viewtopic.jsp?fid=1&topicid=180&tsid=EBE1FBA59D7CF504C31B9157FEF543CA026EADD6FF837599
B题
http://jgjwc.bjtu.edu.cn:8080/bjtumcm/jforum/jforum.viewtopic.jsp?fid=1&topicid=179&tsid=EBE1FBA59D7CF50446A5B86A86DBFFE4265AA031F23D8862
