Here is a "best friend" of C++ programmer — undefined behavior(UB). This is what happens when you try to access index out of bounds. C++ does not offer tool to check range of indexes in bare arrays.

It is what it sounds like — what happens is undefined. It can work properly(often when you access less than +20 elements or so), it can cause freeze of program, it can be anything. In your case it caused TLE.

I advise you to read more on undefined behavior and what can invoke it.