Fastenal Software Developer Intern Interview Questions and Answers

More focus on dp,graphs.

Q1. Focus on backend concepts,routing.
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Q2. Question on flood fill algo,backtracking.
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Round duration - 30 minutes
Round difficulty - Easy

2 easy problems for coding.

Q1. All Prime Numbers less than or equal to N
You are given a positive integer 'N'. Your task is to return all the prime numbers less than or equal to the 'N'.
Note:
1) A prime number is a n...read more
Ans. 
Use sieve to find prime numbers.
Answered by CodingNinjas
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Q2. Absolute difference in an array
You are given an array/list 'ARR' consisting of 'N' non - negative integers. Your task is to return the running absolute difference of the elements at even a...read more
Ans. 
Iterate over array and calculate answers.
Answered by CodingNinjas
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Round duration - 30 minutes
Round difficulty - Hard

Face to face interview, design and coding involved.

Q1. DBMS Question
Given a database of some records. Read records from there and using a formula, calculate maximum speed of cars.
Ans. 
Use data file handling concepts to read and write data in file, used easy arithmetic to find answer.
Answered by CodingNinjas
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Round duration - 60 minutes
Round difficulty - Medium

6 students from the campus were selected for this round. The interviews were conducted simultaneously for all on BlueJeans along with a code sharing website. After the initial set up and introduction, a set of 2 questions from DSA were asked from all candidates. The results were announced the same day.

Q1. DFS Traversal
Given an undirected and disconnected graph G(V, E), containing 'V' vertices and 'E' edges, the information about edges is given using 'GRAPH' matrix, where i-th edge i...read more
Ans. DFS For Each Connected Component
• Run a loop from 0 to V-1 and if this vertex is not visited do a DFS from this vertex and add all the reachable vertex to a vector/list ‘singleComponent’.
• Sort the singleComponent vector/list in increasing order and add it to the answer vector/list which is called ‘components’.
• Print the size of the vector/list ‘components’ on the first line.
• On each line after the first, print one sing...read more
Answered by CodingNinjas
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Q2.  Median of two sorted arrays
You are given two sorted arrays 'A' & 'B' of sizes 'N' & 'M'. You need to find the median of the two arrays when merged. If the total nu...read more
Ans. 
Step 1 : Tried out a few test cases on my own and checked for the output.
Step 2 : Using the linear approach, merged the sorted arrays by iterating over both of them and finding the mid point of the sorted and merged array.
Note: The time complexity for this solution was O(m+n) This wasn't the most optimised solution, a better solution can be given which solves the question in O(log m+log n)
Answered by CodingNinjas
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Round duration - 75 minutes
Round difficulty - Easy

Timing it is around 11 am and Environment is good .

Q1. Bird and maximum fruit-gathering
There are ‘N’ trees in a circle. Each tree has a fruit value associated with it. A ninja bird eyeing the fruits on the tree is blazingly fast. It can sit on a tree for 0.5 ...read more
Ans. Brute Force
We will iterate through the trees with the help of a nested loop. Where we will further loop for the given number of seconds ‘m’, checking for every sum that we obtain is the maximum sum or not and update the sum on each iteration if it is maximum.
 
The algorithm will be-
1. We will run a loop from the starting tree of the given list.
2. Now from every tree, we will run a loop and traverse the remaining trees an...read more
Answered by CodingNinjas
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Q2. Base 58
You are given a number N. Your goal is to convert the number into base 58.
The Base58 alphabet consists of the following characters: “123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz”
...read more
Ans.  base 58
You can represent the integers as powers of 58 and then convert them using the above mapping.
 
Eg: 4364 =  1 * (58 ^ 2)+ 17 * (58 ^ 1) + 14 * (58 ^ 0)
1 in base 10 = 2 in base 58, 17 in base 10 = 2 in base J, 14 in base 10 = 2 in base F
Therefore the answer will be: 2JF
 
Algorithm:
• If the number itself is 0, the answer is 1, else we do the following until the number reaches 0.
  • First, we Initiate an emp...read more
Answered by CodingNinjas
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Round duration - 45 mintues
Round difficulty - Medium

Environment was very friendly but questions asked are hard

Q1. Pair Sum
You are given an array/list ‘ARR’ consisting of ‘N’ distinct integers arranged in ascending order. You are also given an integer ‘TARGET’. Your task is to count all the distinct pairs in ‘ARR’ suc...read more
Ans. Brute Force
First, we declare a variable 'COUNTPAIR’ in which we store all pairs whose sum is equal to 'TARGET’. Then, we traverse the array ‘ARR’ and assume every element as the first element of the pair. Then we again traverse the remaining array and consider every element as a second element of the pair, and check whether the sum of the two elements is equal to 'TARGET' or not. If it is equal to 'TARGET',’ then we in...read more
Answered by CodingNinjas
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Q2. Triplets with Given Sum
You are given an array/list ARR consisting of N integers. Your task is to find all the distinct triplets present in the array which adds up to a given number K.
An array is said t...read more
Ans. Brute Force
• The most trivial approach would be to find all triplets of the array and count all such triplets whose ‘SUM’ = 'K'.
• We can find the answer using three nested loops for three different indexes and check if the values at those indexes sum up to 'K'.
• Create a set  to keep the track of triplets we have visited. Run first loop from i = 0 to i = ‘N’ - 3, second loop from j = i + 1 to j = ‘N’ - 2 and third loop ...read more
Answered by CodingNinjas
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