From what we have already gotten in the first challenge, it is with little difficulty for us to find his personal website:
http://cseweb.ucsd.edu/~dakane
And then, according to the website, we know that he mainly teach two courses: CSE 101 (algorithms) and Math 184 (combinatorics). Find all slides PDFs in the website and search "skyline", we get nothing.
So we continue using tricks we have used in the first challenge, mainly using search engine grammars `site:` and `intext:`:
```site:http://cseweb.ucsd.edu/~dakane intext:skyline```
and find two results. By opening [the first PDF](https://cseweb.ucsd.edu/~dakane/CSE101%20Problem%20Archive/F18/Homework3.pdf), we can find the flag in it:
```sdctf{N1ce_d0rKiNG_C@pt41N}```