DE Shaw interview questions

[Andy Nguyen]

1)Give difference between structure and union and demonstrate union uses with examples.

2)Given a triangle, how do you divide it into 5 triangles of equal area?

3)Given a linked list,find whether a loop exists in it or not,if yes then return a pointer to the start node of the loop?

4)Give a pseudo code to reverse a linked list using recursion.

5)Give a data structure using stack to implement push,pop,min as O(1) operations.

6)Given an array of integers, for each element report the corresponding nearest element greater than it and to the right side of it or a -1 if there exists no such element.
Sample: input: 4 6 2 7 5 4 6 2 output: 6 7 7 -1 6 6 -1 -1

7) Implement a stack using a queue.

8)Throw some light on TCP Handshaking.

9)Throw some light on Denial of service.

10)Give differences between HTTP and HTTPs

 

[GoIllini]

1)Give difference between structure and union and demonstrate union uses with examples.

2)Given a triangle, how do you divide it into 5 triangles of equal area?

3)Given a linked list,find whether a loop exists in it or not,if yes then return a pointer to the start node of the loop?

4)Give a pseudo code to reverse a linked list using recursion.

5)Give a data structure using stack to implement push,pop,min as O(1) operations.

6)Given an array of integers, for each element report the corresponding nearest element greater than it and to the right side of it or a -1 if there exists no such element.
Sample: input: 4 6 2 7 5 4 6 2 output: 6 7 7 -1 6 6 -1 -1

7) Implement a stack using a queue.

8)Throw some light on TCP Handshaking.

9)Throw some light on Denial of service.

10)Give differences between HTTP and HTTPs

Sounds more like a technology interview than a markets interview. Was this for a quant position?

 

[Spurious]

1. What is the area covered in in 14 minutes by the minute hand of a clock of length 15 cm ?
2. What is the diameter of a wheel if it covers 440 m in 1000 revolutions?
3. There are 1 Re, 50 p, 25 p coins in the ratio 3:3:4 respectively. if the total amount is Rs.550, how many 1 Re coins are there?
   ans: 300
4. if A can do 1/3rd of work in 4 days and B can do 1/6th of work in 3 days, then in how many days can both A and B complete the work.
   ans: 7 1/7 days
5. if a number is divided by 935 remainder is 69. if same no. is divided by 38, what will be the remainder?
   ans: 29
6. if a tank is filled by 10 pumps, it takes 12 hours. if the same tank is filled by 15 pumps, then it will take 6 hours. how much time will it take to fill the tank if 25 pumps are used?
7. what is the probability of having b'days of 2 persons on the same day in a gathering of 50 persons?
8. how many words can be formed by the letters of the word DELCIOUS starting with D and ending with E?
   ans: 6! = 720
9. if a man works for 3 hours he gets Rs.15 + 1 meal. if he works for 12 hours he gets Rs.90 + 2 meals. what is the cost of a meal?
   ans: Rs.15/-
10. if a tank can be filled by pipe A in 24 mins and by pipe B in 32 mins. if A and B both are open, when should B be stopped to fill the tank in 18 mins.

I know this is an old post, but maybe someone has the time to help me.​

If someone could check if I am correct here, I would be grateful.​

1. 84​

2. 52.5 pi​

3. 300 (same as in quote)​

My solution:​

3x + 3 * x/2 + 4 * x/4 = 550​

5.5x = 550​

x = 100​

3x = 300, that's the number of coins.​

4. 7.2 days
I got a different solution as above and I was wondering where I went wrong:​

A: needs 12 days to complete the work​

B: needs 18 days to complete the work​

So the formula should be (imo):​

(1/12 + 1/18) * x = 1​

x = 36/5 = 7.2​

Where did I go wrong?​

5. 29, which is one lower than 30.​

Again, where did I go wrong?​

My solution:​

(x+69)/935=1​

x = 866​

So in the second step:​

866/38 = 22.78947​

And 38 * 0.78947 = 30​

​

6. Basically same as 4:​

(1/12 + 1/6) = 1/x --> x = 4​

​

7. The probability that at least two people got the same birthday in a group of 50 is given by:​

P = 1 - 365! / (365-50)!*365^50​

Now, the question asks for 2 people, not at least 2, how do I have to change the formula to reflect that?​

​

8. (same solution as in quote)​

There are 6 letters, because D and E have to be at the beginning and end.​

The solution is 6!.​

​

9. (same solution as in quote)​

4*(15+1M) = 90+2M​

2M = 30 --> M = 15​

​

10. Almost the same as in 4 and 6:​

Pipe A will pump x amount of water into the tank in 18minutes:​

x = 1/24 * 18 --> x=3/4​

Pipe B needs y minutes to fill 1/4 of the tank:​

1/32 * y = 1/4 --> y = 8​

 

[Tsotne]

Generally asking, what is the average time for completion such quiz?

 

[Lyosha]

If it is a written quiz typically you will be given enough time to do roughly half at interviews. Oral quiz lengths depend on your level of aptitude.

 

[pratikpoddar]

No. these are questions I found online. here is another one

[D. E. Shaw, a financial firm in NYC] You and a friend are trying to perform the following "magic" trick. Your friend leaves the room. You hand a standard deck of 52 cards to someone in the audience. The audience member chooses any five cards from the deck and hands those five cards to you.
Now, you must select one of these cards to keep concealed from your friend, and you must display the other four cards side-by-side on a table

Your friend now enters the room, examines the only the four displayed cards, and then tells the audience what's on the concealed card. (Whoa -- what a neat trick!)

Can you and your friend come up with a scheme so that, based solely on the four displayed cards, the fifth card can always be determined?

This is very interesting. I saw this in Peter Winkler's book. Just sharing an interesting thought. At the first look, one feels that its not possible because permutation of 4 cards represent 24 different outcomes and the fifth card can be any of the 48 cards. So, this should not be possible. But the trick here is that fifth card is selected by you. That offers another degree of freedom.

 

[pratikpoddar]

I think there should be a way.

With 4 cards on the table, we are left with 48 in the deck for the friend to guess from. If we agree on seniority of the cards (dimonds => hearts => spades => clubs), we can use the 4 cards on the table as fixed letters A, B, C, D. There are 24 permutations of letters A, B, C, D. If we are to put them horizontally or vertically, it would add anoter 24+24 = 48 ways. Now recalling the seniority of the cards, we find the number from 1 to 48 corresponding to our card and arrange the permutation so that the permutation tells which of the 48 combinations we pick.

For example, the card I have is SQ, and the four others are DQ, H7, H9, CK. Sorted by seniority, they correspond to letters A=DQ, B=H7, C=H9, D=CK.
My SQ card is the 37th in the sequence of 52, but with 4 removed, it is 34th in the sequence of 48. 34 is #10 in the second sequence of 24.
So let the first 24 be horizontal position, and the second 24 be vertical position of my 4 cards.
Now let say we've agreed on the following permutations of A, B, C, D.
A B C D
A B D C
A C B D
A C D B
A D B C
A D C B
B A C D
B A D C
B C A D
B C D A
B D A C
B D C A
C A B D
C A D B
C B A D
C B D A
C D A B
C D B A
D A B C
D A C B
D B A C
D B C A
D C A B
D C B A
Now that my card is encoded as B C D A , I arrange the four cards as H7, H9, CK, DQ vertically on the table, my friend can reverse-engineer my code

You are supposed to keep the cards side by side. Vertically is not allowed. The only information the other guy should have is the permutation. Nothing else.

-- http://www.pratikpoddarcse.blogspot.com