Cheng xuanyuan's story

The story is as follows:

Cheng xuanyuan left the library carrying a pile of books (n.

The alarm rang. The old lady swept the floor and asked her to see which book sounded the alarm. Xu yuan poured out the book and prepared a test.

The old lady was in a hurry and split the book into two parts. The first copy passed and rang.

I divided this one into two parts and went on the test. I found it three times. The old lady swept the floor with the eyes of the Thunderer, as if he was talking about O (N) and O (log2n) cannot tell.

This story seems to be saying that even the old lady who swept the floor will have a binary algorithm (Master in the civil society). Cheng xuanyuan, a programmer, actually needs a test...

The truth of the story is as follows:

As a programmer, Cheng xuanyuan won't use the binary algorithm. She cleverly used the Sweeping Old Lady's binary algorithm to successfully "borrow" n-1 books from the library.

Because the story does not assume that the alarm book is a book.