1. Department of Public Basic Teaching and Research, Shandong Police College, Jinan 250014, China
2. School of Mathematics and Big Data, Foshan University, Guangdong 52800, China
3. School of Information Science and Technology, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
4. College of Mathematics and Statistics, Chongqing University, Chongqing 401331, China