I was solving this problem 2003D2 - Turtle and a MEX Problem (Hard Version).
I have made two submissions on that Accepted on G++17 278425043, Runtime error on G++20 278423515.
The code on both of the submissions is the same, but i do not know why this code isn't being accepted on G++20.
Can anyone explain this strange behaviour.
I am not sure, but maybe it is because you don't return anything from DFS. It has long long type and in many other languages (to be honest, as I know all languages except C and C++) you will get RE. But sometimes it can occur in C and C++, so maybe it is the case.