I made a submission 83580212 to the problem 166A - Rank List and got a wrong answer to test case 15

I have encountered such errors while in contest that the code runs in my terminal but not in online judge

I am using the MinG terminal c++-14

Tried googling the problems but couldnot figure out the main issues. Can someone suggest the problem with code and extra flags i should use while compiling to avoid such blunders

I was solving the problem 198A - About Bacteria and did a submission 81944790 and got wrong answer on case 77 I saw someone's submission which was exactly same with the only difference being the handling of the log expression 81942702 I really cant understand if I have two double a,b; how is log(a) - log(b) different from log(a*1.0/b)