Because in an under-constrained problem there could be multiple solutions. So suppose I want to capture all of them or print all of them out.

因为在一个非约束性问题中,可能会有多组答案,所以假设我想把它们,全部获取或者全部输出。

麻省理工公开课 - 计算机科学及编程导论课程节选

Whenever I think about how to build an interesting program, and I hope whenever you think about it, the first thing I think about is, what are the classes I might want to have, what are the types?

无论我何时,去想怎样建立一个有趣的程序，你们每次做这种思考的时候，你们想得第一件事，就是我应该要有什么类呢，它们是什么类型的呢？

麻省理工公开课 - 计算机科学及编程导论课程节选