可以证明，这种递归解法需要耗费指数级的时间。

It can be shown that this recursive solution takes exponential time to run.

youdao

它让我们看到了，在复杂度依照时间总数来看，没有变化的情况下，递归是怎么一步步的展开的，我欠你一个糖，谢谢。

But that's also nice, it lets you see how the recursive thing is simply unwrapping but the complexity in terms of the amount of time it takes is going to be the same.

youdao

r表示递归；- p表示保持该文件的时间戳。

The -r causes recursion; the -p preserves the time stamps of the files.

youdao

But that's also nice, it lets you see how the recursive thing is simply unwrapping but the complexity in terms of the amount of time it takes is going to be the same.

它让我们看到了，在复杂度依照时间总数来看,没有变化的情况下,递归是怎么一步步的展开的,我欠你一个糖，谢谢。

麻省理工公开课 - 计算机科学及编程导论课程节选