Funding for this research was provided by:
National Natural Science Foundation of China (11461046, 11671246)
National Natural Science Foundation of China (91730303, 11371102)
Division of Computing and Communication Foundations (1527104)
Division of Mathematical Sciences (1719620)
Article History
Received: 10 April 2018
Revised: 6 November 2018
Accepted: 7 January 2019
First Online: 1 February 2019