Flipkart Software Developer Intern Interview Questions, Process, and Tips

Round duration - 65 minutes
Round difficulty - Medium

This online assessment comprised of 12 questions with 2 coding questions and 10 MCQs.
Coding Questions:
It was one of the most common Dynamic Programming problems: Longest decreasing sub-sequence.
It was an easy question that needed us to find out the mean, median and mode in an array.

Q1. Longest Decreasing Subsequence
You are given an array/list ARR consisting of N integers. Your task is to find the length of the longest decreasing subsequence.
A subsequence is a sequence of numbers obta...read more
Ans.  Recursive
We can use recursion to solve this problem.
1. For each element, there are two possibilities.
   1. We include the current item in LDS if it is smaller than the previous element and recurse for remaining items.
   2. We exclude the current item from LDS and recurse for remaining items.
2. Finally, we return the length of LDS we get by including or excluding the current item.
3. The base case of the recursion would be to return 0 when ...read more
Answered by CodingNinjas
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Q2. Remove All The Palindromes
Sushant is learning about palindromes. One day his teacher gave him a string ‘STR’ consisting of only the lowercase letters and asked him to modify the string in such a way that ...read more
Ans. Greedy Approach
The basic idea of this approach is to remove all the palindromes of length two and three. The idea is that if there exists a palindromic substring larger than length 3 then a palindrome of length 2 or 3 is present. 

Here is the algorithm:
 
1. Declare a variable ‘COUNT’ which stores the minimum number of replacements.
2. Declaring another variable ‘CHANGECHAR’ which will store the ASCII value of capital ...read more
Answered by CodingNinjas
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Round duration - 45 minutes
Round difficulty - Medium

There was only one interviewer, I was asked one coding question followed by one puzzle.

Q1. Ways To Make Coin Change
You are given an infinite supply of coins of each of denominations D = {D0, D1, D2, D3, ...... Dn-1}. You need to figure out the total number of ways W, in which you can make a cha...read more
Ans. Recursion
 
1. The idea is to use recursion.
2. For a particular coin, we have two options either include it or exclude it.
3. If we include that coin, then calculate the remaining number that we have to generate so recur for that remaining number.
4. If we exclude that coin, then recur for the same amount that we have to make.
5. Our final answer would be the total number of ways either by including or excluding.
6. There will be two edg...read more
Answered by CodingNinjas
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Q2. Puzzle
There are 3 mislabeled jars, with apple and oranges in the first and second jar respectively. The third jar contains a mixture of apples and oranges. You can pick as many fruits as required to precis...read more
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Round duration - 60 minutes
Round difficulty - Hard

This round was held on Hackerearth and had 2 questions of Medium-Hard difficulty. Both were based on concepts of DP.
The use of offline IDE was prohibited so we were supposed to code it on Hackerearth IDE itself. I was able to code the second problem well with only 3 Test Cases failing but was stuck on the first problem for quite a long time and wasn't able to pass all the major Test Cases .

Q1. Binary Tree Cameras
Given a binary tree, we need to install cameras on the nodes of the tree. Each camera at a node monitors its parent, itself, and its immediate children. Calculate the minimum number of ...read more
Ans. 
Approach : 

Every node has two options either it can have a camera or it cannot. If a node has a camera, then it definitely covers itself, and if it doesn’t have a camera then there are two options either the children nodes cover the current node or the parent node covers the current node. 

A node can be of three types-

Case - 0: ‘CURRENT_NODE’ is not monitored but all nodes in the subtree are monitored.
Case - 1...read more
Answered by CodingNinjas
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Q2. Longest Palindromic Substring
You are given a string (STR) of length N.
Your task is to find the longest palindromic substring. If there is more than one palindromic substring with the maximum length, re...read more
Ans. 
Approach :
1) Create a 2-D dp boolean vector(with all false initially) where dp[i][j] states whether s[i...j] is a palindrome or not and initilialise a variable ans=1 which will store the final answer.

2) Base Case : For every i from 0 to n-1 fill dp[i][i]=1 ( as a single character is always a palindrome ) .

3) Now, run 2 loops first one from i=n-1 to i=0 (i.e., tarverse from the back of the string) and the second one fro...read more
Answered by CodingNinjas
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