On scanhex → Codeforces Round #534, 5 years ago +3 Can someone explain what the hell is going on with pretest 1 to div1B, div2D?
 On den2204 → Codeforces Round #532 (Div. 2) — Editorial, 5 years ago +3 while(kx!=500&&ky!=500) Should be || instead &&.
 On awoo → Educational Codeforces Round 56 [Rated for Div. 2], 5 years ago 0 Can anyone explain solution to E with ordered statistics set? I saw few codes that get AC but I don't understand them all. And what does this magic loop: for(int i = x; i <= n; i += i & -i) 
 On awoo → Educational Codeforces Round 56 [Rated for Div. 2], 5 years ago 0 Graph doesn't have to be connected. Here is example: n = 3 * 10^5, m = 0 Then this part: Spoilerfor (int v = 1; v <= n; v++) { if (visited[v] == false) { color_vertex(v, 0); long long red = 0, black = 0; for (int i = 1; i <= n; i++) { if (visited[i]) { if (colored[i] == 0) red++; else if (colored[i] == 1) black++; } } ans += (1 << red) % MOD + (1 << black) % MOD; ans %= MOD; } } will take n^2 time. Another bug in your code is in this line: ans += (1 << red) % MOD + (1 << black) % MOD; black and red can be bigger than 64. Better option is to just count every 2^k % MOD at the start of your program: POT[0] = 1; for (int i = 1; i < N; i++) POT[i] = (POT[i - 1] * 2) % mod; 
 On awoo → Educational Codeforces Round 56 [Rated for Div. 2], 5 years ago +3 In problem E you have to divide both permutations to blocks of length sqrt(n) and than make some calculations.
 On awoo → Educational Codeforces Round 56 [Rated for Div. 2], 5 years ago 0 Graph doesn't have to be connected.
 On cookiedoth → Codeforces Round #526, 5 years ago 0 Can someone give me some links where I can learn about convex hull opt? The old ones that are on codeforces blog's does not work.
 On danya.smelskiy → Codeforces Round #524 (Div. 2), 6 years ago +4 I don't really understand why problems like C appears in contest like this. I could understand it, if contest would have 5h.But excluding this task contest was really good prepared and there wasn't dos attack during the contest ;)
 On Ashishgup → Codeforces Round #523 (Div. 2), 6 years ago +4 And computers become faster and faster nowadays. It's not like 10^6 operations will take 1 second...
 On Ashishgup → Codeforces Round #523 (Div. 2), 6 years ago +43 Yes, that was nice. This contest was really well written. All tasks have pretty good and short solutions. Thanks to Ashishgup for that contest.
 On Ashishgup → Codeforces Round #523 (Div. 2), 6 years ago 0 I have the same idea, but haven't enough time to debug.This solution should be good. You have at lest 1/4 chance to find this leafs if you take two random vertices.
 On Kniaz → Codeforces Round #392 (Div. 2), 7 years ago +4 OK, it's small probability. But if he has more than 50 accounts? Mabye there is a person who starts in contests to have a high rating...
 On Kniaz → Codeforces Round #392 (Div. 2), 7 years ago +6 Maybe someone is cheating and has two accounts: at one he sends wrong solutions, and from another he hacks...
 On Kniaz → Codeforces Round #392 (Div. 2), 7 years ago +18 Thanks Kniaz for writing problems. I like tasks A, B, E, F very much, D is OK, but problem C is terrible. I hate this type. A lot of commands 'if', 'else'. But it's only my liking. So excluding problem C contest was pretty good.