About the Authors

Zheng Chang

Contributed equally to this work with: Zheng Chang, Zhenjia Wang

Affiliation School of Mathematics, Shandong University, Jinan, Shandong, China

Zhenjia Wang

Contributed equally to this work with: Zheng Chang, Zhenjia Wang

Affiliation School of Mathematics, Shandong University, Jinan, Shandong, China

Guojun Li

guojunsdu@gmail.com

Affiliation School of Mathematics, Shandong University, Jinan, Shandong, China

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: GL ZC. Performed the experiments: ZC ZW. Analyzed the data: ZC ZW. Wrote the paper: ZC. Revised the manuscript: GL.