Codeforces Round #604 Editorial [tutorial:1265A] <spoiler summary="Python Solution"> ~~~~~ T = int(input()) for tc in range(T): s = [c for c in input()] n = len(s) i = 0 while (i < n): if (s[i] == '?'): prv = 'd' if i == 0 else s[i - 1] nxt = 'e' if i + 1 >= n else s[i + 1] for x in ['a', 'b', 'c']: if (x != prv) and (x != nxt): s[i] = x break else: i += 1 ok = True for i in range(n - 1): if (s[i] == s[i + 1]): print("-1") ok = False break if (ok == True): print("".join(s)) ~~~~~ </spoiler> Author: [user:isaf27,2019-12-07], prepare [user:laoriu,2019-12-07], [user:I_love_Hoang_Yen,2019-12-07][tutorial:1265A] [tutorial:1265B] <spoiler summary="C++ solution"> ~~~~~ #include <bits/stdc++.h> using namespace std; const int M = 2e5 + 239; int n, p[M], x; void s...

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Codeforces Round #604 (div1 & div2) Hello everyone! I am glad to invite you to [Codeforces Round #604](https://codeforces.me/contests/1264,1265), which will take place on [contest_time:1264]. The round will be rated for both divisions. Exactly 300 Codeforces rounds passed since my first one (Round 304). I have learned a lot of things here and have much fun in participating in the competitions. Now, I want to contribute to this community by proposing some problems. I hope that you will find something interesting in solving them. The contest is prepared by me, [user:laoriu,2019-12-04], [user:I_love_Hoang_Yen,2019-12-04], coordinator [user:isaf27,2019-12-04] and CF admin [user:MikeMirzayanov,2019-12-04]. As usually, we must specially thank to below people who make contest possible: - [user:MikeMirzayanov,2019-12-04] for the powerful Polygon and Codeforces system. - [user:isaf27,2019-12-04] for coordinating the round. - [user:Um_nik,2019-12-04], [user:arsijo,2019-12-04], [user:opukittpceno_hhr,2019-12-04], ...

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Invitation to CodeChef December Cook-Off 2017! <p>Hello CodeForces Community!</p> <p>To keep the coding clock ticking, we have some interesting challenges in the upcoming December Cook-Off. Joining me on the problem setting panel are:</p> <ul> <li>Problem Setter: [user:chemthan,2017-12-23] (Trung Nguyen)</li> <li>Tester: [user:kingofnumbers,2017-12-23] (Hasan Jaddouh)</li> <li>Editorialist: [user:likecs,2017-12-23] (Bhuvnesh Jain) </li> <li>Admin: [user:kingofnumbers,2017-12-23] (Hasan Jaddouh) </li> <li>Statement Verifier: [user:Xellos,2017-12-23] (Jakub Safin)</li> <li>Russian Translator: [user:CherryTree,2017-12-23] (Sergey Kulik)</li> <li>Mandarin Translator: [user:huzecong,2017-12-23] (Hu Zecong) </li> <li>Vietnamese Translator: VNOI Team </li> </ul> <p><b>All statements are short and clear</b>. I hope you will enjoy solving them. Please give your feedback on the problem set in the comments below, after the contest. </p> <p><b>Contest Details</b>:</p> <p>Time: 24th December 2017 (2130 hrs) to 25th December 2017 (...

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Is chemthan hacked? There was a blog that [user:chemthan,2019-03-20] got hacked, and indeed I got strange messages from his account, asking for help with problems from the next Google Kickstart. The blog is now deleted. It would be nice to hear from some friends of his whether everything is ok now. [user:chemthan1,2019-03-20] is allegedly his temporary alt account. Also, [user:ikatanic,2019-03-20] was mentioned. I can remove this blog a few days after everything is resolved, if [user:chemthan,2019-03-20] wishes so.

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Invitation to CodeChef June Lunchtime 2020 We invite you to participate in CodeChef’s [June Lunchtime](http://bit.ly/LTIME85-Codeforces), this Saturday, 27th June, from [7:30 pm to 10:30 pm IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=June+Lunchtime+2020&iso=20200627T1930&p1=44&ah=3). 3 hours, 5 problems. We will also be hosting a **live problem discussion sessions** where our panelist, [user:RestingRajarshi,2020-06-26] will discuss the Lunchtime problems on [28th June 4 pm to 6 pm IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=CodeChef+June+Lunchtime+-+post-contest+stream&iso=20200628T16&p1=44&ah=2). Find more details [here](https://discuss.codechef.com/t/official-june-lunchtime-2020-post-contest-discussion-live-stream-session/69874). Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them [here](https://www.codechef.com/problemsetting/new-ideas). Joining me on the problem setting panel are: ...

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Invitation to January Easy '19 on HackerEarth  Hello Codeforces community, Since my contribution is gradually decreasing, it is time to stop it :) I would like to invite you to join [HackerEarth's January Easy '19](https://www.hackerearth.com/challenge/competitive/january-easy-19/?utm_source=challenges-modern&utm_campaign=registered-challenges&utm_medium=right-panel) which will start at [15:30 UTC, January 6, 2019](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Hackerearth%27s+January+Easy+%2719&iso=20190106T1530&ah=3). The problems are prepared by [user:aashrayagarwal,2019-01-05], [user:kingofbugs,2019-01-05] and me and tested by [user:zscoder,2019-01-05]. I hope you'll find the problemset to be interesting. You will be given 5 algorithmic problems to solve in 3 hours. Partial scoring will be used (you get points for passing each test case). Although the contest is targeted towards be...

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Invitation to HackerEarth July Circuits '18 Hello everyone! I would like to invite you to participate in [July Circuits '18](https://www.hackerearth.com/challenge/competitive/july-circuits-18/). It's a long contest that will start on Jul 20, 9:00 PM IST ([check you timezone](https://www.timeanddate.com/worldclock/fixedtime.html?msg=July+Circuits+18&iso=20180720T21&p1=176)). Contest will run for 9 days. The problem set consists of 7 traditional algorithmic tasks of various difficulties and 1 approximate problem. For traditional algorithmic tasks, you will receive points for every test case your solution passes — so you can get some points with partial solutions as well. For the approximation task, your score depends on the best solution in the contest so far. Check contest page for more details about in-contest schedule and rules. I'm the setter and [user:lewin,2018-07-20] is the tester. I would like to thank HackerEarth admin panel, without them we do not have such contests. Below is the detail of problem set: - Day-...

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Invitation to HackerEarth February Circuits '19  Hello everyone! I would like to invite you to participate in [February Circuits '19](https://www.hackerearth.com/challenges/competitive/february-circuits-19). It's a long contest that will start on Feb 15, 9:00 PM IST ([check you timezone](https://www.timeanddate.com/worldclock/fixedtime.html?msg=February+Circuits+%2719&iso=20190215T21&p1=176)). Contest will run for 9 days. The problem set consists of 7 traditional algorithmic tasks of various difficulties and 1 approximate problem. For traditional algorithmic tasks, you will receive points for every test case your solution passes — so you can get some points with partial solutions as well. For the approximation task, your score depends on the best solution in the contest so far. Check contest page for more details about in-contest schedule and rules. I'm the tester and [user:Alpha_Q,2019-02-15], [user:aminul,20...

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Invitation to HackerEarth April Circuits '18 Hello everyone! I would like to invite you to participate in [April Circuits '18](https://www.hackerearth.com/challenge/competitive/april-circuits-18/). It's a long contest that will start on Apr 21, 9:00 PM IST ([check you timezone](https://www.timeanddate.com/worldclock/fixedtime.html?msg=April+Circuits+18&iso=20180421T21&p1=176)). Contest will run for 9 days. The problem set consists of 7 traditional algorithmic tasks of various difficulties and 1 approximate problem. For traditional algorithmic tasks, you will receive points for every test case your solution passes — so you can get some points with partial solutions as well. For the approximation task, your score depends on the best solution in the contest so far. Check contest page for more details about in-contest schedule and rules. I'm the tester and [user:mcfx,2018-04-19] is the setter. I would like to thank HackerEarth admin panel, without them we do not have such contests. Below is the detail of problem set: - Da...

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Happy birthday, chemthan ! Hello codeforces! Today is [user:chemthan,2020-11-23]'s birthday. Join me to wish him a very happy birthday. <br> Happy birthday, [user:chemthan,2020-11-23].

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