Hi!
I have two really similar submissions to problem (https://codeforces.net/contest/1266/problem/E)
https://codeforces.net/contest/1266/submission/67209030
https://codeforces.net/contest/1266/submission/67209163
The WA version has the following line:
long long ans = accumulate( a.begin(), a.end(), 0, [] (long long a, long long b) { return a + b; } );
On the AC version, the only change made was this one...
long long ans = accumulate( a.begin(), a.end(), 0ll, [] (long long a, long long b) { return a + b; } );
Why the first one doesn't seem to store the accumulated value in a long long?