Hello codeforces queens

its t7ya back at it again with the fire blogs

so peep this submission:

https://codeforces.net/contest/1702/submission/163553251

this guy avoided getting hacked without having to use neal's unordered map stuff or similar hashing functions. just one include. can anybody explain how this works. is it hackable?

shout out to my man almosabhali. mans a genius