By Interviewbit_is_fraud, history, 3 days ago, ,

Hello, I was enrolled in Interviewbit(Scaler academy) course in May, 2019. I belongs to tier 3 college. Only companies with max 5-6 lack per annum comes to my college. In a hope of getting into good companies I decided to join Interviewbit. I qualified their entrance test which is hard in itself for many average coders in India. Then in a hope of securing good referrals, I used to maintain my Problem solving Percentage above 80% most of time.

When the time of referral come in september — october 2019, they were saying that, right now companies are hiring for on campus and thus we will refer you around November. I believed them. Continued to solve problems working day and night, burning the midnight oil, just in a hope that if I get a referral of good companies.

Now, when when it is november 2019, they came up with new excuse. They told that we are in talk with top tech companies, you will soon hear good news from us. Then many days passed. Nothing happened. I was still hoping that i will get a call soon. In february, I again asked them, I didn't receive call from any company. They said let me check.

Now, I still have to pay 3 lacks to interviewbit as it was mentioned in the contract that even if you get job yourself you will have to pay them. Even they didn't refer me in a single company. Such a shameless people they didn't hesistate to ask money for which their contribution is 0. Now they have removed the cap of 3 lack also. If you secure a job of 16 lacks per annum, you will have to pay 5 lacks to them. Such a huge amount of money for such pathetic things. This money increases with your offer. they are liars , cheaters and fraud. they will have to bear the curse of students.

They have come up with new things in the contract which tells that, you can't publish any statements against them, which may be a concern to company or company's product. They don't want to let their things out to the world, But these duffers don't know that their are many other means to tell people about their true colors.

Let me also tell you their business model, They will not give you referral till the end of session, and when your end of contract date will approach, they will refer you in pathetic companies with ctc just greater that the ctc they provided in contract. Many students who don't have the job offer, in desperation agrees to accept the offer and they still have to pay them. This is their fraud model. dont give referralls, and when session comes to end, try to gain from insecurities of students, refer them in some pathetic startups and claim money.

Here is a blog which lists down problems faced by students who are enrolled.

I just want to tell my juniors that if you have talent, you don't need any other thing. Before joining Inteviewbit I was pretty good in programming. I just joined for referral but they cheated. Please dont let yourself in their trap.

Thank you.

• +578

By C137, history, 8 hours ago, ,

Before Today's round I took part in 197 rated rounds, and I was hoping to mark my 200th round by becoming a master, however my hopes failed as I became master in Today's Round <3 <3 <3

I have been doing CP since February 2015, more than 5 years. Finally today I reached master, I wanted to share this blog with you because I see a lot of times some users say I am not advancing, my rate doesn't change, I am stuck in rate... Believe me in the end everything will change, just be patient and keep believing in your self ;)

You can take a look at all ups and downs in my graph, I didn't reach this level easily, It just takes time.

Happy coding all, I hope you will reach what you want soon.

• +451

By triple__a, history, 3 days ago, ,

1332A - Exercising Walk

Tutorial
Solution (python by pikmike)
Solution (C++)

1332B - Composite Coloring

Tutorial
Solution (python by pikmike)
Solution (C++)

1332C - K-Complete Word

Tutorial
Solution(python by pikmike)
Solution(C++)

1332D - Walk on Matrix

Tutorial
Solution(python by pikmike)

1332E - Height All the Same

Tutorial
Solution 1(python by pikmike)
Solution 2(python by pikmike)

1332F - Independent Set

Tutorial
Solution(C++)

1332G - No Monotone Triples

Contributor of idea of the solution: pikmike

Tutorial
Solution (C++)

• +274

By dreamoon_love_AA, history, 9 hours ago, ,

#### Div.1 C and E are still under construction...

author's code:
author's code:
author's code:
author's code:
author's code:
author's code:

• +44

By Nickolas, 2 days ago, translation, ,

This was the most well-attended April Fools Day Contest in the whole history of them: 10343 participants solved at least one problem! It was also fairly well-balanced: while each problem has been solved by at least 200 participants, only 17 of them solved all 8 problems.

## 1331A - Is it rated?

This was the consolation problem of the contest, and still a lot of participants asked me for hints on this problem — some even before the beginning of the round! If you're still not sure how to solve it, the contest announcement itself promised that the contest is not rated, so the answer is a resolute NO'' (case insensitive, quotes for clarity only) :-)

## 1331B - Limericks

Unusually for this type of contests, the second problem had an actual problem statement! The real task was hidden in it using Steganography 101 — the first letters of the lines spelled out "TWO FACTORS", and a quick look at the examples confirmed that you needed to factor the given number and print its factors (in non-decreasing order, without space between them).

## 1331C - ...And after happily lived ever they

You are probably familiar with the fairy tale ending "... and they lived happily ever after". The problem title is almost that phrase, but with the words scrambled. If you check the problem statement in the other language, it will be a different 6-word phrase that underwent the same scramble. The constraints on the input say that it is an integer are from 0 to 2^6-1; these two things together should push you towards thinking about binary. The solution is as follows: read the input, convert it into a 6-bit binary representation and scramble it in the same way as the words in the title are scrambled (swapping the 2nd with the 6th and the 3rd with the 4th) before converting it back to the integer. You didn't need to worry whether you need to apply the permutation or the inverse permutation, since those two were the same.

## 1331D - Again?

This problem has been written by kit1980.

The answer is just the hexadecimal number given in the input taken modulo 2. The problem is absolutely unrelated to OEIS, same as 656F - Ace It!.

## 1331E - Jordan Smiley

The problem was inspired by the Jordan curve theorem, more specifically by this blog post. You were given the coordinates of a pixel within the picture, and you had to figure out whether it was inside or outside of the region defined by the closed curve that made up the picture.

Once you figured that out, the problem became mostly image parsing :-) The easiest way was to flood-fill the region inside the curve using an image editor, and then somehow convert pixels of different colors into an array of 0s and 1s.

## 1331F - Elementary!

YES or NO answer implies that you need to figure out whether the given word is elementary!''. At a glance this seems elementary, my dear Watson! — but the fact that "HOLMES" is a "NO" while "WATSON" is a "YES" suggests that this is not what's going on here. In fact you were supposed to use another meaning of the word "elementary" — the one of the periodic table of chemical elements. The word was "elementary" if it could be spelled using only the abbreviated symbols of elements: Ge-Ni-U-S or W-At-S-O-N.

## 1331G - Lingua Romana

This problem has been written by kit1980.

The problem statement is actual source code of a program written in Perligata. If you manage to run it (or translate it from Latin, though I wouldn't recommend that!), you might recognize TPK algorithm. After that you can implement it yourself or look it up on RosettaCode.

## 1331H - It's showtime

Both the problem title and the error message you'd get if you try to run some random code like "123" in custom invocation tab point you to an esoteric language ArnoldC — a language based on the one-liners of Arnold Schwarzenegger. You'd have to experiment a bit with finer and less documented points of the language, such as reading input, but modulo function is defined in the documentation, and overall it's a fairly approachable language — as long as you don't try anything fancy like arrays!

• +159

By R2-D2_hates_lemon, history, 9 hours ago, ,

Hi everyone! In recent contests, my friends and I did not perform well. However, our ratings still increased somehow. In addition, CF predictor is no longer precise these days. Maybe I'm not the only one who feel strange. Then, did Codeforces change their formula for rating system?

• +68

By kostia244, 3 days ago, ,

Hello Codeforces! I got some interesting tricks to share with you.

### 1. a_i := (a_i + x)%mod Range Updates, Max Range Queries

Apply usual range addition, but after each update run the following code:

void normalize(int l, int r) {
while(getmax(l, r).max >= mod) {
set(getmax(l, r).pos, getmax(l, r).max%mod);
}
}


What is the complexity of this code? We all know that each time we %%=mod\$ number which is $\geqslant mod$ it halves, that means each number will be updated $O(log)$ times, we will perform $O(n\cdot\log{n}\cdot\log{a})$ operations in total. So each update will be $O(\log{n}\cdot\log{a})$ amortized!

### 2. $O(\log^2{\log{n}})$ Segment Tree

Segment tree queries are queries on path. Instead of doing them in the usual brute force-ish way we can use HLD! Since maximum path length is $2\cdot\log{n}$, thus operations are now operations are $O(\log^2{\log{n}})$, which is better than $O(\log{n})$.

### 3. Faster Dinic's

We know that after $i$ operations Dinic's algo finds flow which is at least $\frac{i}{i+1}\cdot{maxflow}$. In some problems we just want to check whether flow is at least $x$. Using the fact above we can run one iteration of the algorigthm which will get us $\frac{1}{2}$ of maxflow and multiply that by two. Now just compare $x$ and maxflow.

### 4. Linear FFT

Usually, we use roots of unity ($e^{\frac{\tau\cdot t}{n} \cdot i}$) or primitive roots (for ntt). But why would we limit ourselves to those?

Instead of roots of unity, we can choose roots of something else, that looks complex enough. This, for example:

${e^{\sqrt[x]{6 \cdot \pi ^ 2 \cdot \prod_{1 \leqslant i \leqslant 10} {(x - i \cdot x^{\frac{1}{i}})}} + i\cdot\frac{\pi}{2}}} = i$

Let's choose a few roots of this thing which we'll use for FFT. We can notice that $(-1)^{\frac{i}{2\cdot i - 2}}, 1 \leqslant i \leqslant 10$ work. So using them we have $O(10\cdot n) = O(n)$ FFT!

### 5. Linear Interpolation(Actually Point Evaluation Without Finding The Polynomial)

We can interpolate in linear time if given x coordinates of given points are n consequential integers (check out 622F editorial for details). We can use this approach to perform general interpolation in $O(n)$. Let $f$ be the polynomial interpolated, n be the number of points given, $v$ be the x value in which we want to evaluate $f$, $x$ be x coordinates, and $y$ be y coordinates of given points. Let's introduce a new polynomial $g$, such that $g(i) = x_i, 0 \leqslant i \lt n$. We can solve $g(x) = v$ easily using HS math in $O(n)$ time. Now, let's interpolate $h(x) = f(g(x))$ instead of $f(x)$. We just evaluate $h(g^{-1}(x))$ since input of $h$ is n consequential integers we can do it in linear time. Easy as that!

Thanks for reading, I hope your rating will skyrocket after applying those in contest! If you have any questions feel free to leave commments or DM me(kostia244) or AryaPawn

• +421

By galen_colin, 7 hours ago, ,

If you failed on test 66 on (this problem | div2 version), you probably haven't reset enough of your array in between. This problem gives rise to a very unique type of bug, since we access the array beyond the part where we initially read elements into. What I mean is, if you have a large case followed by a small one, on the small one, you'll read the first $2^n - 1$ elements in, but the elements in indices $2^n$ to $2^{n+1}-1$ may also be filled with values from the last test case. Many people adapted the function definition from the problem statement, treating an index like a leaf iff the two elements 'below' it (i.e. $a_{2i}$ and $a_{2i+1}$) are both $0$. But if the array isn't reset, then values that are supposed to be leaves may be treated differently. Unfortunately, I made this mistake too :(

Not resetting the state between test cases is common. But this is a very unique type of mistake, specific to this problem. I don't think it's reasonable to blame the setter for overlooking this in the pretests. Surprising that none of the testers made this same mistake, though...

• +50

By stefdasca, history, 9 hours ago, ,

Hello!

Since the editorials are still not out, I prepared video editorials for div2 B, C and D.

B

C

D

Check the videos and if you liked them, subscribe to the channel for more CP content

• +58

By Lazy_lad, history, 45 hours ago, ,

Most of the times I am absolutely clueless about how to start a question rated above 1500(Div-2 C). Then I look at the editorial ,and I get disappointed on missing the trick. I usually don't face problem in implementing a solution but I do face problem in finding the trick.