I was submitting the solution for Round #362 Div2 Problem E :
http://codeforces.net/contest/697/problem/E
I got WA on Test#4 on this submission : http://codeforces.net/contest/697/submission/19150824 I had typecasted every possible places where I felt overflow could occur with long long. I submitted many times but it gave wrong answer with typecast.
Then I submitted using 1ll in multiplication instead of typecast in this submission and it got accepted: http://codeforces.net/contest/697/submission/19150943
My question is why does typecasting not work and what is the difference between typecasting and 1ll?? Also when to use which because many of the solutions I coded before used typecasts and it worked well on various judges including Codeforces until I encountered this case for the first time.