# Quant dynamic hackerrank

I have applied for the Goldman sachs interview recently, here are the questions that are being asked: Round 1: Online Coding Hacker earth question: 1. There were 2 sections — CS and Quant. You are given 1 hour per section. Goldman Sachs was coming to Hyderabad for a drive.

Round 1: The first round was an Online Test conducted on the Hackerrank platform. Given an integer K and an array height[] where height[i] denotes the height of the ith tree in a forest. Round 1 Online : This was an online test on HackerRank. There were a total of 5 sections in this test. Round 1 minutes : Interviewer was very friendly.

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He started by asking tell me something about yourself. There was also another easy question related to recursion. I contacted the recruiter through LinkedIn and share my resume with them. Within 2 days, he sent me the test link. Hackerrank — input: digit, and arr of numbers — output: count total of that digit in number else reurn -1; 2. I had 2 years of experience when I got a call from Goldman about hiring going on for a certain team.To get a job as a computer programmer on Wall Street or in the City, you may have to pass a HackerRank test.

Here are tips for how to solve the latter. A workaround is to search for the title of the exercise, which uniquely identifies a question on HackerRank and will be mentioned in related solutions posted online, making it perfect for being indexed by Google, according to The HFT Guya London-based developer who has worked at high-frequency trading shops.

Often for basic exercises the first result is the question, and the second result is the solution, which seems easy, but you have to double-check that the solution is correct. In addition, you can rarely find solutions to the most challenging coding exercises online, especially since firms usually write their own questions and exercises.

Here are some of the more difficult sample HackerRank coding exercises and solutions from Martin Kysela Cambridge, Massachusetts-based software engineer at NuoDB, which runs an elastic SQL database for cloud applications. Insertion Sort is a simple sorting technique. Sometimes arrays may be too large for you to wait around for insertion sort to finish, so Kysel suggests another way that you can calculate the number of times Insertion Sort shifts each element when sorting an array.

There are more solutions with nlogn time for this challenge. Kysel decided to use Binary Indexed Trees as they are a data structure I am not that familiar with. The other solution includes a modified merge-sort that is posted as the problem editorial.

BITs are effective for computing cumulative frequencies in log N time and are therefore perfectly suited for this problem. They assume a full tree and therefore are bound to the maximal range defined in the problem specification. You have to rotate the matrix R times and print the resultant matrix. Rotation should be in a counter-clockwise direction. There is just lots of code, but the actual solution is pretty simple, according to Keysel.

First, you extract layers to simplify the logic. Then, you rotate the layers similarly to the Codility Rotation challenge.

Keysel optimized this solution to the minimal case that passes all tests on HackerRank. It seems that each character occurs one or two times.

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If two or more have less or more characters, then there is no way to fix the string in just one removal. If exactly one character has a different count than all other characters, then Keysel says to remove this character completely to fix S.

Contact: dbutcher efinancialcareers. Bear with us if you leave a comment at the bottom of this article: all our comments are moderated by actual human beings. Sometimes these humans might be asleep, or away from their desks, so it may take a while for your comment to appear.

Learn more about it on Wikipedia. The first line contains two space-separated integers, the number of sequences and the number of queriesrespectively. Each of the subsequent lines contains a query in the format defined above. For each type query, print the updated value of on a new line.

Query 0: Append to sequence. Query 1: Append to sequence. Query 2: Append to sequence. Query 3: Assign the value at index of sequence toprint. Query 4: Assign the value at index of sequence toprint. We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.

Practice Compete Jobs Leaderboard. Problem Submissions Leaderboard Discussions Editorial. Create a list,of empty sequences, where each sequence is indexed from to. The elements within each of the sequences also use -indexing. Create an integer,and initialize it to. The types of queries that can be performed on your list of sequences are described below: Query: 1 x y Find the sequence,at index in.

Append integer to sequence. Query: 2 x y Find the sequence,at index in. Find the value of element in where is the size of and assign it to. Print the new value of on a new line Task Given, and queries, execute each query.

Input Format. It is guaranteed that query type will never query an empty sequence or index. Output Format. Sample Input. Sample Output.A college admits students on the basis of their scores in a series of 5 aptitude tests.

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The academic performance of the admitted students is then tracked, and when they complete the first year of their academic program in college, their Grade Point Average GPA is recorded.

Higher the GPA, the better. This exercise is conducted on one batch of students. Absolute GPA is used for this problem. The next year, the college realizes that it does not have the necessary resources to conduct all 5 aptitude tests, it decides to conduct only 1 of the 5 tests. Which of the aptitude tests would you recommend them to conduct for the next round of admissions? You are given the recorded data. Identify the aptitude test which has clearly the best predictive value in determining the relative academic standing of the students after they enter the college.

The 1 st line in the file is an integer T, T testcases follow. Each testcase has 7 lines. The 1 st line of every testcase contains the number of admitted students, N. The 2 nd line of every testcase has N decimal numbers upto 2 decimal places separated by a single space which are the Grade Point Averages GPAs of the admitted students at the end of the 1 st academic year.

The i th score, is the GPA of the i th student at the end of the 1 st year. This next 5 lines of every testcase has N decimal numbers upto 2 decimal places separated by a single space in each line, which is the performance of the students in the 5 aptitude tests conducted for the entrance exam.

The i th integer in each line, is what the i th student scored in that aptitude test. T integers, each on a new line. For each test case, output the Aptitude Test which appears to be the best predictor of the relative academic standing of the students after they enter the college.

In the given example, we can see that the ranks of the students, on the basis of their 1 st year GPA; "matches quite well" with their relative standings in the first aptitude test in which their scores were 10,30,20,40 You need to identify how you can quantify how well the relative standings in an aptitude test match with the relative standings of the GPA.

Assume that for each test case provided, there is one aptitude test, the scores in which, appear to be be good predictors of the academic performance of the students in college measured by GPA. The other aptitude tests do not seem to have much predictive value, and can be done away with.

Input Format The 1 st line in the file is an integer T, T testcases follow. Output Format T integers, each on a new line.

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Sample Input 1 5 7.As a consequence, the tech industry is pushing for longer, harder and evermore extreme screening. The whiteboard interview has been the standard for a while, followed by puzzles [now abandoned], then FizzBuzz. The latest fad is HackerRank. A lot of very good companies are using HackerRank as a pre-screening tool. Any amount of any question can be put together, in any order, to make a complete test. A company should give some indications on what to expect in its test.

HackerRank provides a library of hundreds of questions and exercises ready to use. The majority of the multiple choice questions can be solved by an appropriate Google search. Usually on the title, sometimes on a few select words from the text.

Searching for a 10 lines long paragraph in Google is not an acceptable option. The workaround is to search for the title of the exercise.

A title uniquely identifies a question on HackerRank.

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It will be mentioned in related solutions and blog posts. Perfect for being indexed by Google. The first result is the questionthe second result is the solution. Well, that was easy. Bonus : That google solution is actually wrong… yet it gives all the points. This solution is only correct if duplicated numbers are in pairs.

All the HackerRank unit tests happen to fit this criteria by pure coincidence [cf. Originally, we put this simple question at the beginning of a test for warm-up. We received that answer from a candidate in our first batch of applicants.

It was quite puzzling, what are the odds that someone would come up with an algorithm that convoluted if given only the text from the question? A quick investigation quickly revealed the source. Hence why the solution is off but works. HackerRank is obviously copying questions from the community into the professional library. We have a lot of candidates coming from recruiters.

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How are they comparing to candidates from other sources? It used to. Anyway, we remember approximate numbers. We can correlate that number with the time spent on the question and a visual code review. The result is that candidates coming from recruiters perform better, especially on hard exercises. In fact it is unbelievable how much better they perform! The conclusion is plain and simple: Our recruiters give away the test to the candidates.

Companies can write custom exercises and they should. It is the only effective solution against Google, if done carefully. Excluding the first batch of candidates who will be sacrificed as scouts.

## Algorithms

Did we just ruin HackerRank pre-screening? Of course not! There is a never-ending supply of bozos unable to tell the difference between Internet and Internet Explorer.

This is because nextInt reads just the number, not the end of line or anything after the number. When you call nextLine it reads the remainder of the same line and does not wait for input. Ideally you should call kb. You are commenting using your WordPress.

## Three difficult HackerRank problems – and how to solve them

Email required Address never made public. Name required. By continuing to use this website, you agree to their use. To find out more, including how to control cookies, see here: Cookie Policy.For example, octal form of IPv4 was allowed. So a precceding 0 indicates number in ocatal. For IPv6, :: were allowed to compress the string. They followed up for a phone screen after the online test. It seem if you can do questions, they give you a chance. Q1 - Given coins, 99 unbiased and 1 biased, you randomly choose a coin and flip it 10 times.

You get 10 heads in a row. What is the probability that you chose biased coin?

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Q2 - You go to a casino to play a game which consists of flipping dies with six faces Game 3: You flip three dies and the amount of money you earn is median i, j, k where i is face value of die 1, j is face value of die 2 and k is the face value of die 3. Which game will you play? I was originally thinking the first problem could be solved using a Sieve of Eratosthenes variant, but the large upper bound and small number of divisors made it highly impractical.

Simply iterating through the possibilities seems to work fine:. What does Dynamic mean here? For question 1, the Sieve Erathosthenes does not work well here. You will have to get the complicated variant of prime factorization. Remember when we factorized an Ideal number, it is only divisible by 3 or 5. Because it is is a irreducable,all of its reduced factors have to be divisible by 3 or 5. A much better running time is this. For the phone interview, did they expect you to solve Q1 numerically?

Or would saying "Bayes rule" be enough? I took this as well; I had different questions. Thought mins was way too short to get them all done. I passed all cases for 3 of them and partial for 2. Anonymous User. Last Edit: November 22, PM 5. Q5 Didn't get a chance to even look at it. I was able to pass all test cases for Q3, partial for Q1, Q2 and Q4. Comments: 8. Login to Comment. MikeBonzai Read More. Show 1 reply. Sithis Moderator Show 2 replies.

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Looks pretty difficult for only 2 hours. Did you end up hearing back? I took this as well and got the phone interview but was rejected after that.