Flipkart SDE-2 Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Medium

It was a telephonic interview at 10 in the morning. Interviewer seemed cool.

Q1. 
Best Insert Position for a Target in a Sorted Array
You are provided with a sorted array A of length N consisting of distinct integers and a target integer M. Your task is to determine the position where ...read more
Ans. Brute Force
• Iterate through the given array.
  • If at any position i, we get A[i] ≥ M, return i.
• If there is no such position i, return N.
Space Complexity: O(1)Explanation:
O(1).
 
As there is no extra space required.
Time Complexity: O(n)Explanation:
O(N), where ‘N’ is the length of the given array.
 
We are traversing the array only once. Hence, the overall complexity is O(N).
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Round duration - 60 minutes
Round difficulty - Medium

The interview was in the morning at 10 AM in the office meeting room.

Q1. 
House Robber Problem Statement
Mr. X is a professional robber with a plan to rob houses arranged in a circular street. Each house has a certain amount of money hidden, separated by a security system that ...read more
Ans. 
Didn't get enough time to code the solution but explained the approach
We can do this using DP
We can maintain 2 arrays - one represents the ans if we start from first house and the other represents the answer if we start. from the second house.Then simply looping over the array and calculating these array's elements.
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Round duration - 60 minutes
Round difficulty - Medium

The interview was at 11 AM in the meeting office.

Q1. 
Running Median Problem
Given a stream of integers, calculate and print the median after each new integer is added to the stream.
Output only the integer part of the median.
Example:
Input:
N = 5  
Stre...read more
Ans. 
Started with the brute force solution of insertion sort
Interviewer asked to optimize.
Gave the solution which uses two heaps - max heap and min heap. the difference in size of both heaps cannot be more than 1. And we might need to remove elements from one heap to other heap as more input numbers are added
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Round duration - 60 minutes
Round difficulty - Medium

The interview was at 1 AM.

Round duration - 60 minutes
Round difficulty - Easy

The meeting was at 2 PM in the office meeting room.

Round duration - 60 minutes
Round difficulty - Easy

10 AM

Q1. Can you provide a deeper discussion about all the projects you completed in your previous company?
Ans. 
Tip 1: Know well about the projects that you have done in the past

 
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Round duration - 1hour
Round difficulty - Hard

Q1. 
Snake and Ladder Problem Statement
Given a 'Snake and Ladder' board with N rows and N columns, where positions are numbered from 1 to (N*N) starting from the bottom left, alternating direction each row, f...read more
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Round duration - 1hour
Round difficulty - Hard

Q1.  Stack using queue
Mvvm architecture
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Round duration - 1hour
Round difficulty - Easy

Round duration - 60 minutes
Round difficulty - Easy

Started with brief intro(5 mins) about interviewer.
Problem solving question, question was already there in the codelink shared by the interviewer. He explained the problem again with sample testcase. 
The Interviewer was friendly.

Q1. 
Course Schedule II Problem Statement
You are provided with a number of courses 'N', some of which have prerequisites. There is a matrix named 'PREREQUISITES' of size 'M' x 2. This matrix indicates that fo...read more
Ans. Breadth-First Search
Our current algorithm is based on the idea of the BFS approach. We first process all the courses with 0 in-degree implying no prerequisite courses required. If we remove all these courses from the graph, along with their outgoing edges, we can find out the courses/nodes that should be processed next. These would again be the nodes with 0 in-degree. We can continuously do this until all the courses h...read more
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Q2. Design a live video broadcast platform.
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Round duration - 90 minutes
Round difficulty - Medium

There were 2 interviewers(India HM and Seattle HM), India HM was just shadowing and didn't ask any questions. Started with intro, he asked in detail about what I do at current company(10 mins). Again, jumped into LP's(25 mins).

Q1. 
Distance Between Two Nodes in a Binary Tree
Given a binary tree and the values of two distinct nodes, determine the distance between these two nodes in the tree. The distance is defined as the minimum num...read more
Ans. Naive Approach
In any rooted tree, the distance between two nodes 'U' and 'V' can be found by finding the lowest common ancestor (LCA), ‘x’ of two nodes. The lowest common ancestor (LCA) between nodes 'U' and 'V' is defined as the lowest node in the tree that has both 'U' and 'V' as descendants, where we define each node to be a descendant of itself (so if 'U' has a direct connection from 'V', 'V' is the lowest common a...read more
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Q2. 
Median in a Stream Problem Statement
Your task is to determine the median of integers as they are read from a data stream. The median is the middle value in the ordered list of numbers. If the list length...read more
Ans. Brute force approach
Store the incoming data elements in a vector. Sort the vector everytime you need to output the median.
Algorithm:
1. Store the incoming elements of the data stream in a vector.
2. Step by step insert one element and sort the vector as soon as any element is added in the vector.
3. If the size of the vector is odd, print the middle element of the sorted vector.
   If the size of the vector is even, return the mean of...read more
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Round duration - 60 minutes
Round difficulty - Medium

There was only 1 interviewer in this round and We had no video sharing in this round so it was becoming difficult to understand each other.

Round duration - 60 minutes
Round difficulty - Easy

Timing: evening
Environment: Online round took at home

Q1. 
Smallest Subarray with K Distinct Elements Problem
Given an array A consisting of N integers, find the smallest subarray of A that contains exactly K distinct integers.
Input:
The first line contains tw...read more
Ans. 
At first sight this can be solved easily by using two loops to iterate over contiguous subarrays in O(n^2) and counting number of arrays and breaking the outer loop if number of odds exceed 'k'.

Optimised solution is to take two pointer approach where right pointer is incremented till num of odds not exceed 'k'. If limit is reached, increment left pointer and add number of arrays (right - left+1)*(right-left)/2 to the r
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Round duration - 90 minutes
Round difficulty - Medium

Machine coding round

Round duration - 60 minutes
Round difficulty - Medium

Q1. 
Rat In a Maze Problem Statement
Given a N * N maze with a rat placed at position MAZE[0][0], find and print all possible paths for the rat to reach its destination at MAZE[N-1][N-1]. The rat is allowed to...read more
Ans. Backtracking Approach
Initialize, all the cells of the solution matrix used to print the path matrix to 0. First, you cannot make use of the existing maze to print the solution maze as you have to distinguish b/w 1 of maze or 1 of ‘SOLUTION matrix.
 
Form a recursive function, which will follow a path and check if the path reaches the destination or not. If the path does not reach the destination then backtrack and t...read more
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Round duration - 60-90 minutes
Round difficulty - Medium

Round duration - 60 minutes
Round difficulty - Medium

Hiring Manager round

Round duration - 90 minutes
Round difficulty - Easy

I got a call from an Amazon recruiter regarding the schedule of the test . She sent me the coding test link which I had to complete within a week. we can attempt the online test anytime, when we have time for a period of 90 minutes at a stretch.Once I completed the test, I got a call to schedule the interviews in two weeks.

Q1. 
Shopping Options Problem Statement
Given arrays representing the costs of pants, shirts, shoes, and skirts, and a budget amount 'X', determine the total number of valid combinations that can be purchased ...read more
Ans. Brute Force
We can check all possible combinations to buy items. That can be done by maintaining a variable “answer” and iterating over all four lists in a nested way such that each pant, shirt, shoe, and skirt pair can get selected and find the sum of that pair. If sum is less than or equal to budget then increment “answer” by one. Return the “answer”.

Algorithm:
 
• Create an integer “answer” equal to 0.
• First iterate ...read more
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Q2. 
Max Submatrix Problem Statement
You are provided with a matrix MAT consisting of integers, with dimensions N x M (i.e., N rows and M columns). Your objective is to determine the maximum sum submatrix with...read more
Ans. Brute Force
The brute force approach is we check for every possible submatrix in the given ‘MAT’.
• 4 nested loops are required to select every submatrix of the matrix.
• 2 nested loops are required to take the sum of all the elements of the submatrix.
Here is the algorithm :
1. We declare a variable ‘MAX_SUM’ in which we store the maximum sum over all submatrices in the matrix.
2. We run a loop for ‘i’ = 0 to ‘N’:
   • We run a loop for ‘j...read more
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Round duration - 60 minutes
Round difficulty - Medium

Virtual interview occured in amazon chime.The interviewer gave his introduction, asked me a bit on the kind of projects I’ve worked on. Then he started with a data structure problem.

Q1. 
Clone a Binary Tree with Random Pointers
Given a binary tree where each node has pointers to its left, right, and a random node, create a deep copy of the binary tree.
Input:
The first line contains an ...read more
Ans. HashMap based approach
The idea is to use a HashMap to map the tree nodes to each clone node. We will traverse the binary tree and create a clone tree with the random pointer equal to NULL and map each node of the given tree to its clone node. Now we will again iterate through the tree and add the random pointer of each node by looking up the HashMap. 
 
The steps are as follows:
1. Let’s define a HashMap to map eac...read more
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Q2. 
The Ninja Port Problem
Ninja is in a city with 'N' colonies, where each colony contains 'K' houses. He starts at house number "sourceHouse" in colony number "sourceColony" and wants to reach house number ...read more
Ans. Breadth First Search
We can initially create a graph with 2 nodes from each colony i.e. the first and last house of each colony would be included in the graph. We also create an edge from the node representing the last node of each colony to the node representing the first node of the next colony, and vice versa.
 
Now, we add into the graph each house that has an outgoing or incoming secret path. We also make edges ...read more
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Round duration - 75 Minutes
Round difficulty - Easy

This was taken by an engineering manager who asked me regarding my projects for around 10-15 mins and then we moved to a system design problem. He asked me to design Slack messenger.
I started by listing the functional and non-functional requirements(on which he questioned me a bit), then I moved to draw the high-level architecture. The components which I drew were the clients, gateway service(LB + authentication, etc), Messaging Service, User Service, Web Socket Manager service, Fan Out service(I added this for the group messages thing, but he didn’t interrogate much on that).

He asked me what would be the schema of my messages table and the scenarios in which the recipient user is online/offline.Also asked about the partitioning key and primary key of the 2-3 tables which I had made

Round duration - 60 minutes
Round difficulty - Hard

BarRaiser Round

This was again taken by an engineering manager who discussed my projects in depth for around 20-25 mins. In the remaining time he asked me 2 dsa questions. (Yes I too was surprised that he didn’t ask anything regarding design).

In almost all the rounds, I was asked questions related to Amazon Leadership principles, so do make sure you go through those before sitting for the interview process. You can refer to this link(https://www.codingninjas.com/codestudio/problem-lists/top-amazon-coding-interview-questions) for practicing the same, I found it useful. 
In the design rounds, interviewer doesn’t expect the most ideal answer from you and unless your choice of technology is outrageously wrong, he won’t pinpoint that.

Q1. 
Group Anagrams Together
Given an array/list of strings STR_LIST, group the anagrams together and return each group as a list of strings. Each group must contain strings that are anagrams of each other.
E...read more
Ans. Sorting based Approach
The idea behind this approach is that two or more than two strings are anagrams if and only if their sorted strings are equal. So we will use a HashMap, let’s say “anagramGroup”, where each key is a sorted string, and the key will be mapping to the list of indices from the given list of strings that form a group of anagrams. This means that if we sort the strings at those indices, we will get the ...read more
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Q2. 
Add Two Numbers Represented by Linked Lists
Your task is to find the sum list of two numbers represented by linked lists and return the head of the sum list.
Explanation:
The sum list should be a linked...read more
Ans. Recursive approach
One way is to recursively add the two linked lists. Keep the nodes in the recursion stack and add the last nodes first and then second last and so on. Initially, find the size of both the linked lists. If both the linked lists are of the same size, add them using recursion. Else if their sizes differ, move the head pointer of the larger linked list forward K times, where K is the difference between th...read more
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