1. College of Computer and Cyber Security, Fujian Normal University, Fuzhou, China
2. School of Computer Science and Engineering, Sun Yat-sen University, Guangzhou, China
3. Zhejiang-HUST Joint Research Center for Graph Processing, Zhejiang Lab, Hangzhou, China
4. School of Computer Science and Engineering, University of Aizu, Aizuwakamatsu, Japan