Yesterday, I was trying a problem. I got two different verdict on the apporx same code.
Solution 1 (Accepted) : https://codeforces.net/contest/271/submission/115150455
Solution 2 (Runtime Error) : https://codeforces.net/contest/271/submission/115150580
See line 83 of solution 1. There i have assigned pre[1][2] to some value which is out of bound. But still the code was accepted, it should give Runtime Error as given in the solution 2. In solution 2, I changed long long to int. I submitted another code in which i removed pre[1][2] assignment and then it was accepted.
Solution 3 : https://codeforces.net/contest/271/submission/115150618
Someone please tell why didn't I get RTE in my solution 1 as pre[1][2] is clearly out of bound?
Thanks in advance!
You very lucky. You overwrote some random value in memory, some random variable that is unused or was overwritten later or maybe you wrote a value to padding. Either way you didn't corrupt any data by coincidence.
But why it gave RTE in solution 2? Everything is same as in solution 1, i just changed long long to int in solution 2.
Well,
int
takes 4 bytes in memory,long long
takes 8 bytes in memory. Sovector<int>(2)
allocates (at least in theory) 8 bytes andvector<long long>(2)
allocates 16 bytes, so maybe they used different allocation buckets. Or maybe the size was padded to 16 bytes so there were 8 bytes of unused padding inint
case and no padding inlong long
case.