pointer network

https://zhuanlan.zhihu.com/p/73590690

https://www.jianshu.com/p/2ad389e91467

https://blog.csdn.net/weixin_40240670/article/details/86483896

https://study.163.com/course/courseLearn.htm?courseId=1208991809#/learn/video?lessonId=1278489343&courseId=1208991809