Codeforces Round 1044 (Div. 2) Editorial Thank you for participating in my round! I hope you all enjoyed it. <spoiler summary="Rate the contest!"> <spoiler summary="Quality"> - Excellent contest - Good contest - Average contest - Bad contest - Horrible contest </spoiler> <spoiler summary="Difficulty"> - Trivial contest - Easy contest - Average contest - Hard contest - Impossible contest </spoiler> </spoiler> [problem:2133A] <spoiler summary="Hint 1"> What does the speed of each gear depend on? </spoiler> <spoiler summary="Solution"> Suppose we have some arrangement of gears where gear $i$ from the left has $b_i$ teeth. Then the speed of gear $n$ is $1 \cdot \frac{b_1}{b_2} \cdot \frac{b_2}{b_3} \cdot \ldots \cdot \frac{b_{n-1}}{b_n}$. Notice that most of the fractions cancel, leaving only $\frac{b_1}{b_n}$. So in fact, the speed of gear $n$ depends only on $b_n...

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Educational Codeforces Round 58 Editorial [problem:1101A] <spoiler summary="Tutorial"> [tutorial:1101A] </spoiler> <spoiler summary="Solution (BledDest)"> ~~~~~ q = int(input()) for i in range(q): l, r, d = map(int, input().split()) if(d < l or d > r): print(d) else: print((r // d) * d + d) ~~~~~ </spoiler> [problem:1101B] <spoiler summary="Tutorial"> [tutorial:1101B] </spoiler> <spoiler summary="Solution (Vovuh)"> ~~~~~ #include <bits/stdc++.h> using namespace std; void rem(string &s, const string &c) { auto pos = s.find(c); if (pos == string::npos) { cout << -1 << endl; exit(0); } s.erase(0, pos + 1); } int main() { #ifdef _DEBUG freopen("input.txt", "r", stdin); // freopen("output.txt", "w", stdout); #endif string s; cin >> s; rem(s, "["); rem(s, ":"); reverse(s.begin(), s.end()); rem(s, "]"); rem(s, ":"); cout << count(s.begin(), s.end(), '|') + 4 << endl; return 0; } ~~~~~ </spoiler> [pro...

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Codeforces Round #411 Hi! I'd like to invite you to join in Codeforces Round #411 that will be held on [May 4 at 17:35 MSK](https://www.timeanddate.com/worldclock/fixedtime.html?day=4&month=5&year=2017&hour=17&min=35&sec=0&p1=166). Actually I didn't do anything for this contest :) and most of the contest is prepared by my good friends [user:ChamrAn,2017-05-03] and [user:MohammadJA,2017-05-03]. Also [user:Hifdah,2017-05-03], [user:Navick,2017-05-03], [user:Folorn,2017-05-03], [user:kastarika,2017-05-03] and I helped them in testing problems, writing statements and these sort of things. At the end, Thanks to [user:KAN,2017-05-03] for his huge help in all of the contests and [user:MikeMirzayanov,2017-05-03] for great Codeforces and Polygon platforms. (Sorry if there's someone I didn't mentioned, This is everything I know). Each division contains 6 problems (4 common problems). Hope you enjoy them. The round is rated and score distribution will be posted soon and good luck and have fun and hope you ...

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Codeforces Round #219 Statistics [contest:372] and [contest:373] statistics (with images) [cut] : <pre> <code> --------------------------------------------------------------------------------------------- | Codeforces Round #219 (Div. 1) | --------------------------------------------------------------------------------------------- | | First | Sent | Pretest | Hacked | Systest | Accepted | Attempts | Success | Severity | | | | | failed | | failed | | | % | | --------------------------------------------------------------------------------------------- | A | 00:03 | 672 | 120 | 4 | 58 | 490 | 1461 | 33.5 | 1.98 | | B | 00:09 | 411 | 15 | 1 | 28 | 367 | 466 | 78.8 | 1.11 | | C | 00:23 | 237 | 68 | 0 | 12 | 157 | 428 | 36.7 | 1.66 | | D | 00:59 | 28 | 5 | 0 | 1 | 22 ...

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Educational Codeforces Round 63 [Rated for Div. 2] Hello Codeforces! On [contest_time:1155] [contest:1155] will start. Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://mirror.codeforces.com/blog/entry/51208">blog post</a>. This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally. You will be given **6 problems** and **2 hours** to solve them. The problems were invented and prepared by Roman [user:Roms,2019-04-21] Glazov, Adilbek [user:adedalic,2019-04-21] Dalabaev, Vladimir [user:Vovuh,2019-04-21] Petrov, Ivan [user:Bl...

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Codeforces Round #411 Editorial We were waiting several weeks to setting this contest and hope the problem was good enough. #### Events There was a difficulty with [problem:805E]/[problem:804C]. A little bug in the checker fortunately yields accepting an incorrect solution of only one person during the contest. I should apologize all of you because of this. For this sentence, `Vertices which have the i-th (1 ≤ i ≤ m) type of ice cream form a connected subgraph.` You can find the meaning of "connected subgraph" with [connected](http://mathworld.wolfram.com/ConnectedGraph.html) and [subgraph](http://www.edmath.org/MATtours/discrete/concepts/csubgr.html), thus it can be empty as it is more logical. How ever, I should apologize all of the participants because of weak sample tests in the statement. I will write the full editorial in the few next days, now some hints and short solutions exist here. Hints ------------------ [problem:805A] <spoiler summary="hint1"> Almost half of numbers are divisible by two...

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