It took me seven comparisons, because I can take advantage of the fact I know I only ever have to look at the first element of each sub-list. Those are the only things I need to compare, and when I run out of one list, I just add the rest of the list in.

进行了7次对比，因为我可以利用我知道的优势：,每次只需要比较每个子列表的第一个元素,那才是我需要进行对比的内容,当一个列表的元素处理完了,只需要将另一个列表剩下的元素直接添加进去。

麻省理工公开课 - 计算机科学及编程导论课程节选