something to consider when looking at their C2 CE submission is how they forgot to include the cstdint header for uint64_t (which is basically unsigned long long).

program.cpp: In function 'void solve()':
program.cpp:63:12: error: 'uint64_t' was not declared in this scope
   63 |     vector<uint64_t> cands;
      |            ^~~~~~~~
program.cpp:16:1: note: 'uint64_t' is defined in header '<cstdint>'; did you forget to '#include <cstdint>'?
   15 | #include <iomanip>
  +++ |+#include <cstdint>
   16 |

so it might just be a mistake after all, it doesn't take too much time to insert #include <cstdint> in that code/template.

furthermore, they might have added using ull = unsigned long long after that error, and also I personally do not think AI would be "smart" enough to write stoull (string to ull function) instead of either making an entire function for it or using some other built-in function that is very straightforward. something like that.

still, it doesn't hurt to prepare for the worst (especially since they solved E1), i'm just sharing my opinion here.

did you really, really have to reveal their info like that

orz lgm

so i'm pretty sure this wasn't stolen from last year

chess battle advanced

my friends are sending pictures of them becoming lgm right now