# Junior data scientist Interview Questions in United Kingdom

# 2K

Junior Data Scientist interview questions shared by candidates### For a given array count combination of pairs of (x,y) whose sum is N.

4 Answers↳

int[] list = {7,6,2,3,4,5}; int N=9; int count=0; for(int i=0;i

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Three solutions I gave. 1. Sort the array in O(nlogn). Min and Max as two indices. Count=0 Loop if A[Min]+A[Max]N Decrement (Max) else Increment(Count) End 2. Using extra space and count sort if the minima and maxima of array sets are in a given range. Max absolute negative number subtracted to keep numbers in positive number space. Loop if Memory[N- A[i]- Min] Increment(Count) End 3. Create a Hashset/Hashtable. Look for N-A[i] and increment count if found. Loop if Get(N- A[i]) Increment (Count) else Push(A[i]) End Less

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the complexity of ur solution is not so good you can do better

### If a jar has X red balls and Y blue balls, what is the minimum number of draws that is necessary to ensure that you have one ball of each color?

3 Answers↳

It is max, the first reply was correct. I you have 5 blue balls and 2 red balls : - If it was min : you take 3 balls, it is still possible to have picked 3 blue balls. - with max : you take 6 balls, the worst case is that you have picked 5 blue and 1 red balls. Less

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max(X, Y)+1

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min(X,Y) + 1 is correct, not max()

### How would you query an SQL database with Tera of data?

2 Answers↳

Not sure of the answer but would try to partition my query.

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I would probably batch my data

### A frog falls down a well of 50ft. Each day he climbs up 3 and each night falls down 2. How many days does it take him to get out?

2 Answers↳

48 actually

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47

### Find out whether an array/string contains non-repeated characters.

2 Answers↳

Two solutions I gave 1. Make a bucket of ASCII (256),/ Eng Alphabet(26)characters.Look for count of A[i] . If 1 return false else return true in the end Loop if (!Memory[A[i]]) ) Increment (Count) else return false End return true 2. Create a Hashset/Hashtable. Look for A[i] . If found return false else return true in the end Loop if ! Get(A[i]) Push (A[i]) else return false End return true Less

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the complxity of your solution will be O(n) runtime and O(n) memory you can do better Less

### If the coefficient of an independent variable in linear regression has an opposite sign than it should be, what might be the reason

1 Answers↳

multicollinearity

### Introductory questions. Describing yourself. Your skills. Your past experiences. Presentation of a Case Study that was provided a few days before the interview.

1 Answers↳

I answered honestly. I sounded genuine and friendly. Smiling all the time. Presented the Case Study and answered the questions that followed. Less