Department of Computer Science and Engineering;
Chongqing University;
Chongqing 400044;
China;
Department of Mathematics and Computer Science;
Chongqing Normal University;
Chongqing 400047;
China;
Department of Modem Educational Technology;
Chongqing Normal University;
Chongqing 400047;
China;
Department of Mathematics;
Leshan Normal College;
Leshan 610043;
Sichuan;
China;