National Instruments

National Instruments Interview Questions and Tips

1

National Instruments Software engineer internship interview

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PC GowthamFresherSelected
Application
I was interviewed on-campus at JSS Mahavidyapeetha Sri Jayachamarajendra College of Engineering, Mysore for Software engineer role at National Instruments
Interview Process
Test Coding Round Technical Interview
Round 1

Test

Duration
90 Minutes
No. of Questions
10 questions
Test Sections
    Interview Experience
    • 1 question was on time complexity of searching an unsorted array.
    • 2 questions were on recursion, ie, number of recursive calls.
    • 1 question on analysing given function on string.
    • 1 question was on probability(Two hotels, say A and B. Probability of moving from A to B is 2/3, staying at A is 1/3. Probability of moving from B to A and staying at B is 1/2. If they make decisions each hour, and if they were at A at 7:00 pm, what is the probability that they will be at B at 10:00 pm).
    • If a set has elements {1,2,3,4 .... n}. Then what is the sum of elements of it's power set. (Ex: S = {1,2}. Then power set is {{},{1},{2},{1,2}}. The sum is 6.
    • If a set has elements {1,2,3,4,5,6,7,8,9,10}. Then how many subsets of 3 elements has no consecutive elements.
    • 1 question was on designing a DFA for a string starting with a and ending with c and has at least b in it.
    • 1 question had machine instructions. We had to find out minimum number of cycles needed to execute the given set of instructions. (a) If the instructions are executed in the given order. (b) If the instructions are executed in random order.
    • 1 puzzle on bridges.
    Interview Tips
    In this round they not only see the answer. They also verify how you approached(So, give correct explanation to your answers).
    Round 2

    Coding Round

    Interview Experience
    Two questions were there. 3 hours duration.

    1. Long question, I don't remember fully. I'll just give input/output examples. It was basically on string decoding. If jon2snow3 is there the decoded string will be jonjonsnowjonjonsnowjonjonsnow. Given a string and an integer k we have print the kth character in the decoded string
    input:
    jon2snow3
    8
    output:
    n

    2. Given an array and an integer k return the number of contiguous sub arrays whose sum is divisible by k.
    input format:
    n k
    <n elements of the array>
    input:
    4 5
    10 0 4 5

    output:
    4

    explaination: {10},{0},{10,0},{5} are the sub arrays with sum divisible by 5.

    Interview Tips
    You will have lots of time, so try to optimise the solution if you can. Remember here also they review each individual's code.
    Round 3

    Technical Interview

    Interview Questions
    • Question 1: They asked me optimise the code I had written for the first question
    • Question 2: Given a binary tree, find out the maximum sum path from root to leaf. This problem, but they said tree has only positive integers. http://www.geeksforgeeks.org/find-the-maximum-sum-path-in-a-binary-tree/ . To store the path I had used global array. They asked me alternative to global array, I said passing array as parameter. Then they asked me about disadvantages of using global variables.
    • Question 3: Given a list of words. Given three operations find out the minimum steps to reach from source string to destination string. Basically, http://www.geeksforgeeks.org/length-of-shortest-chain-to-reach-a-target-word/ this is the problem with some modification. For this question I said I will use graph traversal techniques. So, they started asking about BFS and DFS, when to use them.
    Interview Experience
    They will help you a lot if you are stuck at some point in the question. You have to be smart enough to grasp the clue.
    Interview Tips
    They only ask questions only on data structures and algorithms.
    Skills

    Skills Tested

    • C Programming
    • Maths(esp Probability)
    • Algorithms And Data Structures
    Skill Tips
    You have to be strong in coding. Algorithm questions will be mostly on dynamic programming. Data structures questions are mostly on trees.
    Resources

    Preparation materials

    Books
    • C Aptitude:Test Your C Skills By Yeshvant Kanetkar,
    • Coding Interview Questions : Narasimha Karumanchi,
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