Hello Codeforces!

Computer Club, MNNIT Allahabad, India is glad to invite you to the annual programming competition of MNNIT, Insomnia, which is an ACM-ICPC style team programming contest of 2.5 hours duration held on Codeforces during its annual technical fest Avishkar. The team can consist of up to 3 members.

Contest Details:

• Qualifiers:

  • Start Time: Saturday, March 16, 22:30 IST
  • Duration: 2.5 hours

• Finals:

  • Start Time: Monday, March 18, 12:00 IST
  • Duration: 3 hours

The Top 25 global teams and the Top 25 teams from MNNIT (based on the result of Qualifiers) will qualify for the Finals. The prize distribution for global teams is mentioned below:

Teams consisting of MNNIT students only will be eligible for a separate prize pool.

Register your team for the qualifiers here. [For Non-Mnnitians only]

Also, self-register your team directly on codeforces here

Problem setters: coderdhanraj, sshivendra764, lalit_1471, anonymous_2211, kantan and Sun_Tzu

Testers: 18o3, vrintle, GoatTamer, and Phantom_Deluxe.

We have an exciting problemset awaiting you. Good luck and have fun!

UPD1: Qualifiers is postponed to Saturday, March 16, 22:30 IST.

UPD2: Registrations are started for Qualifiers.

UPD3: Here is the list of invited teams for the Final Round of INSOMNIA 2024. The invite link has been shared to the mail of the team leader submitted in the google form. (Please check your spam as well)

If your team is on the list and still you have not received any mail then please reach out to me on codeforces.

UPD4: Due to unforeseen circumstances, today's contest has been postponed to tomorrow. We apologize for any inconvenience caused. The updated schedule is March 19, 2024, from 10:00 AM to 1:00 PM IST

UPD5: Hope you guys enjoyed both the sets.

Here are the winners of the finals:

Global teams:

1. Windchime: IceKnight1093
2. tbd: shiven, GenghizKhan, keyurchd_11

MNNIT Teams:

1. Blitz: ace01, Vinayak286, Aadersh_Chaubey
2. MugiWara: aryanguptaaa, arsh.1709, arpit.ras
3. BahutPeechheRehGaye: lucifer223, NishuOne8, utkarsh1236

One can try problems of finals here

After approximately $$$3$$$ years of consistency and hard work, I finally have the happiest moment of my life I reached Candidate Master!

Hello Everyone!

Recently I was exploring Codeforces APIs and thought that there is a need for an extension that shows problem difficulty as well as all the contest problems links together (as usually it takes some time switching from status/submission/problem page to dashboard to select a desired problem).

So, well here it is!
With the help of this extension, one can go through any problem to any other problem easily (also can go to a problem from status/submission/hack pages to the desired problem).

You can try this extension.

Steps to follow (for the installation)

Right now I haven't deployed/uploaded it on either Chrome or Firefox but you can install it locally!
You just have to clone this repo or can download via zip and load/unpack the folder over the chrome/firefox extension (with developer mode on). (guide for chrome)

UPD: To use this without unpacking the extension just copy-paste this userscript in tampermonkey or a similar tool.

UPD2: Updated the verdict thing as well. You can enter your codeforces handle to make verdict color work!

UPD3: Updated userscript is here. (Thanks to normankr07)

UPD4: The extension is now live on Mozilla Add-ons. 😇

UPD5: Updated the show/hide rating thing (check the repo).

Any suggestion would be helpful!

Happy Coding :)

Hello Codeforces!

I would like to invite you to take part in HackerEarth's July Easy '23! It will be held on Saturday, July 1, 2023 at 9:30 AM IST.

The problems were written and tested by me (Dhanraj coderdhanraj Chaurasia), Rangey 18o3 Raghav, Anushk Anushk-24 Gautam, Rajat rajat397 Srivastava and Rohit rohit_768_ Pradhan.

Also, many thanks to Ujjwal ujjwald7 Dwivedi for coordinating the contest.

You will be given 6 algorithmic problems to solve in 3 hours. Partial scoring will be used (i.e. you get points for passing each test case).

Although the contest is targeted toward beginners, we hope that everyone finds the tasks interesting. The contest is rated for all and the prizes will be awarded to the top 3 beginners (i.e. participants with a rating less than 1600 before the challenge starts):

• First place: $75 Amazon gift card.
• Second place: $50 Amazon gift card.
• Third place: $25 Amazon gift card.

UPD: Registrations are started!

Good luck everyone, and feel free to discuss the problems here when the contest ends.

Hello Codeforces!

I would like to invite you to take part in HackerEarth's May Easy '23! It will be held on Saturday, May 6, 2023 at 9:30 AM IST.

The problems were written and tested by me (Dhanraj coderdhanraj Chaurasia), Pawankumar EulerTour Nandagiri, Devanshul SilverWing05 Saraswat, Akshit strange14 Garg, Rohit rohit_768_ Pradhan and Suchit Atlas K.

Also, many thanks to Ujjwal ujjwald7 Dwivedi for coordinating the contest.

You will be given 6 algorithmic problems to solve in 3 hours. Partial scoring will be used (i.e. you get points for passing each test case).

Although the contest is targeted toward beginners, we hope that everyone finds the tasks interesting. The contest is rated for all and the prizes will be awarded to the top 3 beginners (i.e. participants with a rating less than 1600 before the challenge starts):

• First place: $75 Amazon gift card.
• Second place: $50 Amazon gift card.
• Third place: $25 Amazon gift card.

UPD: The contest is now rescheduled to Saturday, May 13, 2023 at 11:30 AM IST. You can register for the contest here.

UPD2: Hackerearth May DSA '23 will be held on Saturday, May 13, 2023 at 09:30 AM IST.

Good luck everyone, and feel free to discuss the problems here when the contest ends.

Hey Everyone!

First of all, "Merry Christmas" and "Happy New Year" to all, hope you all would be doing good :)

Hack #1: Fix Background for Dark Reader

As codeforces's looks gets changed between christmas and new year's eves so due to change in background some of us who use dark reader or any dark themes would be facing issues while exploring codeforces.

So if you facing the same issue you may do following to get the following result :)

You just need to add the following code to dev tool of "Dark Reader" for "codeforces.com" under "CSS".

body{
    background:url(..) !important;
}

Hack #2: Remove/Hide Tags for Codeforces Problems

As you would have to download any additional extension to hide the tags. Or you may be disabling the tags for unsolved problems via codeforces settings(but once a problem get solved tags get visible!).

So to remove problem tags. Add the following code to dev tool of "Dark Reader" for "codeforces.com" under "CSS".

.tag-box{
    display:none;
}

If you want to see the problem difficuly(rating) only, then add the following code as well!

span[title="Difficulty"]{
    display:block;
}

Hack #3: Be pro on codechef (Remove the pro banners on codechef)

You just need to add the following code to dev tool of "Dark Reader" for "codechef.com" under "CSS". to be pro XD.

.special-block-img-container,
.m-premium-text-container{
    display:none;
}

Hack #4: Upto you :)

Similarly above you may change styling of a website to get the desired result :3

If you find this blog useful then press the green triangle :)

Hey Everyone!

Hope you all would be doing great! I recently was exploring some codeforces chrome extensions and I came across following underrated extensions which are not that famous but they are pretty much useful.

• Coding Shout (It gives a message stating verdict of your current submission) it's pretty much useful as during a contest we usually don't want to stay on 'my submission page' to get the verdict.

• CF GetRating (It hides the tags and shows only the problem difficulty) it's pretty much useful during practice as we don't want to see the tags but want to get an idea of problem difficulty.

• CF Tracker (It's a kind of stopwatch which may help in practice to speed up)

If there are more useful extensions do let me know in the comments I will add those in the blog. :)

PS: I got a working userscript for Multirating graph here (work like this).

Hey Everyone,

I am stuck on the following problem. Need help!

Problem: Unique Paths (Hard Version)

You are given a grid consisting of $$$n$$$ rows and $$$m$$$ columns. There are two types of cells good and bad. You can't move in a bad cell. There are $$$k$$$ bad cells in the grid.

You can move only in the right and down direction only. i.e. if you are on cell $$$(i, j)$$$, so you can move to $$$(i + 1, j)$$$ and $$$(i, j + 1)$$$.

You are asked to find the no of ways or no of unique paths to reach cell $$$(n, m)$$$ from cell $$$(1, 1)$$$. As the answer can be large print it modulo $$${10^9 + 7}$$$.

Constraints:

$$${1 \le n, m\le 10^5}$$$, $$${0 \le k \le min(10^3, n * m).}$$$

Sample Example

n = 5, m = 5, k = 2.

bad cells = (1, 2), (3, 3).

answer = 17.

Hey Everyone!, I was trying this problem with Matrix Exponential as I got a recurrence relation of $$${f_k = f_{k-9} + f_{k-10}}$$$.

I am unable to speed up the matrix exponentiation as it's gonna be $$${O(10^3 * log k)}$$$ to get Matrix $$$M_{10 * 10}^k$$$ to get $$$f_k$$$.

Can anyone tell me some optimizations to get $$$f_k$$$ faster?

Hey Everyone,

Recently, I had my Salesforces Coding Test and I got 3 problems in which I solved 2 problems fully and solved the following problem partially with $$$O(n * m * m)$$$ using DP. Can anyone tell me the $$$O(n)$$$ approach for this problem?

Problem : Bob and Problems

Bob and Alice are preparing $$$n$$$ problems for Hackerrank. [n-problem together can be considered as 1 problem-set]

The hardness level of the problem $$$i$$$ will be an integer $$$a_i$$$, where $$$a_i \ge 0.$$$

The hardness of the problems in a given problem-set must satisfy $$$a_i + a_{i + 1} < m$$$, and $$$a_1 + a_n < m$$$, where $$$m$$$ is a fixed integer.

Bob wants to know how many different problem-set are possible. And since this number can be huge, he wants Alice to find it under modulo $$$998244353$$$.

Note :

1. Two problem-sets of difficulty $$$a$$$ and $$$b$$$ are different only if there is an integer $$$j$$$ ($$$1 \le i \le n$$$) satisfying $$$a_i \neq a_j$$$.

2. You can choose $$$a_i$$$ as any integer greater than or equal to $$$0$$$, as long as it satisfies the constraints on line-3.

Constrains :

$$$2 \le n \le 10^5$$$, $$$1 \le m \le 10^9$$$

Sample Test Case :

Input : 3 2

Output : 4

Explanation :

The valid different problem-sets are [0, 0, 0], [0, 0, 1], [0, 1, 0], [1, 0, 0].

[1, 0, 1] is invalid since $$$a_1 + a_n \ge m$$$ here.

Hey Everyone,

Hope you all doing well, as we all know Codeforces is one of the best sites on the internet. I would like to suggest some features if codeforces can add then codeforces would become way better.

• Hide Tags but show problem difficulty/rating option.
• A rated/unrated registration policy. [I have seen this feature on atcoder.jp]
• A streak ranking leaderboard (shows the coders having highest streak). [I have seen this feature on kenkooo.com]
• An official dark theme.
• Score distribution for gym/mashups contests, same as we see in a Div2/Div1/Global rounds.

These are just my personal suggestions. What additional feature would you suggest?

Hey everyone! I recently learned Binay-Lifting and found a problem Tree Number Generator. I am getting WA on 5th test case but I am unable to see the test case because it's disabled, here is my code.

Can anyone help me finding the counter-case for my submission or letting me know where I am doing wrong.

Thanks in Advanced :)

Hello Everyone!!

I will be making mashups daily in this group so that everyone can practice improving their problem-solving skills. The contests would be consist of 8 problems and two and half an hour [150 minutes] to solve them for now and having an 800-1500 rating difficulties, would be increasing with time. I will also be making some topic-wise mashups every week (e.g. Binary Search, Bitmasking, Graphs, Dynamic Programming. etc) so that those who are weak in these topics can improve it and those who are good at it, can make their speed.

In the group, there would be an overall leaderboard (IFMO typed) (containing all occurred contests scores) so that a better competitive environment exists.

The overall Leaderboard Sample can be shown below:

Anyone can join this group to participate in daily contests (mashups).

I will be waiting to see many participants in today's contest. Daily contests would be at 20:05 UTC, when a clash occurs with any real contest then the practice contest would not occur on that day.

Thank you.