Flipkart Software Developer Interview Questions, Process, and Tips

It will be mostly DSA for freshers. 1 easy 1 medium question

Round 2 interview was a coding interview too. 2 questions asked. one implementation and another topological sort

Q1. About my projects and challenges i faced
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Round duration - 60 Minutes
Round difficulty - Medium

The round was held on Google Meet and I was given 2 coding problems for which first I had to explain my approach and then I had to write code in Shared Google Docs and dry run on sample test cases and discuss Time and Space Complexity. After the coding problems , I was asked some basic theoretical concepts from Data Structures and Time Complexities.

There were 2 interviewers and both were very friendly and helpful and tried to bring us to our comfort level first.

Q1. 
Smallest Window Problem Statement
Given two strings S and X containing random characters, the task is to find the smallest substring in S which contains all the characters present in X.
Input:
The first...read more
Ans. 
Find the smallest substring in S containing all characters in X.
• Use a sliding window approach to find the smallest window in S containing all characters in X.

• Keep track of the characters in X using a hashmap.

• Slide the window to the right until all characters in X are found, then shrink the window from the left to find the smallest window.
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Q2. 
Pythagorean Triplets Detection
Determine if an array contains a Pythagorean triplet by checking whether there are three integers x, y, and z such that x² + y² = z² within the array.
Input:
The first lin...read more
Ans. 
Detect if an array contains a Pythagorean triplet by checking if there are three integers x, y, and z such that x^2 + y^2 = z^2.
• Iterate through all possible triplets of numbers in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations of three numbers from the array.

• Check if the sum of squares of two numbers is equal to the square of the third number for each trip...read more
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Q3. What is the time complexity of retrieving the minimum element from a max heap?
Ans. 
The time complexity of retrieving the minimum element from a max heap is O(1).
• Retrieving the minimum element from a max heap involves accessing the root node, which is always the minimum element in a max heap.

• Since the root node can be directly accessed in constant time, the time complexity is O(1).
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Round duration - 60 Minutes
Round difficulty - Medium

This was also a Data Structures and Algorithms round where I was asked to solve 2 coding problems explaining my approach with proper Complexity Analysis . After the coding questions were over there was some time left so the interviewer asked me an interesting puzzle just to check my aptitude.

Q1. 
Median of Subarrays of Specific Size
Given an integer array ARR of size N and a specified subarray size M, calculate and return the median of all subarrays of size M starting from the left of the array.
...read more
Ans. 
Calculate and return the median of all subarrays of a specified size in an integer array.
• Iterate through the array and for each subarray of size M, calculate the median.

• If the size of the subarray is even, take the average of the two middle numbers as the median.

• Return the list of medians for all subarrays of size M.
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Q2. 
Validate BST Problem Statement
Given a binary tree with N nodes, determine whether the tree is a Binary Search Tree (BST). If it is a BST, return true; otherwise, return false.
A binary search tree (BST)...read more
Ans. 
Validate if a given binary tree is a Binary Search Tree (BST) or not.
• Check if the left subtree of a node contains only nodes with data less than the node's data.

• Check if the right subtree of a node contains only nodes with data greater than the node's data.

• Recursively check if both the left and right subtrees are also binary search trees.
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Round duration - 50 Minutes
Round difficulty - Medium

In this round I was first asked to implement a Phone Book , which required the knowledge of Trie and then I was asked a question related to Memory Management and External Sorting . I was able to answer both of them with proper explanation and codes.

Q1. 
Phone Directory Search Directory
You are given a list/array of strings representing the contacts in a phone directory. The task is to perform a search based on a query string 'str' and return all contacts...read more
Ans. 
Implement a phone directory search feature to suggest contacts based on a query string prefix.
• Iterate through the contact list to find contacts with the prefix matching the query string.

• Display suggestions as the user types each character of the query.

• Handle cases where no suggestions are found for a particular prefix by printing 'No suggestions found'.
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Q2. 
Counting Sort Problem Statement
Ninja is learning about sorting algorithms, specifically those that do not rely on comparisons. Can you help Ninja implement the counting sort algorithm?
Example:
Input:
...read more
Ans. 
Implement counting sort algorithm to sort an array of integers without comparisons.
• Count the frequency of each element in the input array.

• Calculate the prefix sum of frequencies to determine the position of each element in the sorted array.

• Build the sorted array based on the prefix sum.

• Time complexity of counting sort is O(n+k), where n is the number of elements and k is the range of input.

• Example: Input array {-2, 1,
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Round duration - 50 Minutes
Round difficulty - Medium

The round was held on Google Meet and I was given 2 coding problems for which first I had to explain my approach and then I had to write code in Shared Google Docs and dry run on sample test cases and discuss Time and Space Complexity. After the coding problems , I was asked some basic theoretical concepts from Data Structures and Time Complexities.

There were 2 interviewers and both were very friendly and helpful and tried to bring us to our comfort level first.

Q1. 
Add Two Numbers as Linked Lists
You are given two singly linked lists, where each list represents a positive number without any leading zeros.
Your task is to add these two numbers and return the sum as ...read more
Ans. 
Add two numbers represented as linked lists and return the sum as a linked list.
• Traverse both linked lists simultaneously while adding corresponding nodes and carry over the sum if needed

• Handle cases where one linked list is longer than the other by considering carry over

• Create a new linked list to store the sum and return its head node
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Q2. 
Maximum Sum Path from Leaf to Root
Given a binary tree with 'N' nodes, identify the path from a leaf node to the root node that has the maximum sum among all root-to-leaf paths.
Example:
All the possibl...read more
Ans. 
Find the path from a leaf node to the root node with the maximum sum in a binary tree.
• Traverse the binary tree from leaf to root, keeping track of the sum along each path.

• Compare the sums of all root-to-leaf paths and find the path with the maximum sum.

• Implement a recursive function to traverse the tree and calculate the sum of each path.
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Q3. What is the time complexity of retrieving the minimum element from a max heap?
Ans. 
The time complexity of retrieving the minimum element from a max heap is O(1).
• Retrieving the minimum element from a max heap involves accessing the root node, which is always the minimum element in a max heap.

• Since the root node can be directly accessed in constant time, the time complexity is O(1).
Answered by AI
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Round duration - 50 Minutes
Round difficulty - Medium

This was also a Data Structures and Algorithm round where I was asked to solve 2 medium to hard level problems along with their pseudo code within 50 minutes . Later I was also tested on some basic questions related to Sorting Algorithms.

Q1. 
Kth Ancestor in a Binary Tree
You are given an arbitrary binary tree consisting of N nodes numbered from 1 to N, an integer K, and a node TARGET_NODE_VAL from the tree. Your task is to find the Kth ancest...read more
Ans. 
Find the Kth ancestor of a given node in a binary tree.
• Traverse the tree to find the path from the target node to the root node.

• Keep track of the ancestors in a list while traversing.

• Return the Kth ancestor from the list, or -1 if it doesn't exist.
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Q2. 
Find All Triplets with Zero Sum
Given an array Arr consisting of N integers, find all distinct triplets in the array that sum up to zero.
Explanation:
An array is said to have a triplet {Arr[i], Arr[j],...read more
Ans. 
Find all distinct triplets in an array that sum up to zero.
• Use a nested loop to iterate through all possible triplets in the array.

• Sort the array to easily identify duplicates and skip them.

• Check for triplets with sum zero and add them to the result list.
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Round duration - 50 minutes
Round difficulty - Medium

This round was also held on Google Meet where I was supposed to code 2 problems in a Google Doc. After the coding questions , I was asked some core concepts related to OS . 
Both the interviewers were quite friendly and helpful. Overall it was a good experience.

Q1. 
Reverse Linked List Problem Statement
Given a Singly Linked List of integers, your task is to reverse the Linked List by altering the links between the nodes.
Input:
The first line of input is an intege...read more
Ans. 
Reverse a singly linked list by altering the links between nodes.
• Iterate through the linked list and reverse the links between nodes

• Use three pointers to keep track of the current, previous, and next nodes

• Update the links between nodes to reverse the list

• Return the head of the reversed linked list
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Q2. 
Find K-th Smallest Element in BST
Given a binary search tree (BST) and an integer K, the task is to find the K-th smallest element in the BST.
Example:
Input:
BST: Order of elements in increasing order...read more
Ans. 
Find the K-th smallest element in a binary search tree (BST).
• Perform an in-order traversal of the BST to get elements in increasing order.

• Keep track of the count of visited nodes to find the K-th smallest element.

• Return the K-th smallest element once the count matches K.
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Q3. What do you mean by FCFS?
Ans. 
FCFS stands for First-Come, First-Served. It is a scheduling algorithm used in operating systems.
• FCFS is a non-preemptive scheduling algorithm where the process that arrives first is executed first.

• It is a simple and easy-to-understand scheduling algorithm.

• Example: If processes P1, P2, and P3 arrive in that order, they will be executed in the same order - P1, P2, P3.

• FCFS can lead to the problem of 'convoy effect' where...read more
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Q4. What is thrashing in operating systems?
Ans. 
Thrashing in operating systems occurs when the system is spending more time swapping data between memory and disk than actually executing tasks.
• Occurs when the system is constantly swapping data between memory and disk

• Causes a significant decrease in performance as the system is unable to effectively execute tasks

• Usually happens when the system is overloaded with too many processes or lacks sufficient memory

• Can be miti...read more
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Round duration - 40 Minutes
Round difficulty - Easy

The online coding test is not that difficult. The questions are very easy. Only thing is that you have to come up with an efficient solution.The naive solutions are fairly obvious.

Q1. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Using stack approach : 

1) Store the nodes(values and address) in the stack until all the values are entered.
2) Once all entries are done, Update the Head pointer to the last location(i.e the last value).
3) Start popping the nodes(value and address) and store them in the same order until the stack is empty.
4) Update the next pointer of last Node in the stack by NULL.
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Round duration - 50 Minutes
Round difficulty - Easy

First question was very simple. I was asked for the solution first and then to write the code on paper and show it to him.Second question requires more time to think.

Q1. 
Circular Move Problem Statement
You have a robot currently positioned at the origin (0, 0) on a two-dimensional grid, facing the north direction. You are given a sequence of moves in the form of a string ...read more
Ans. 
The idea is to consider the starting position as (0, 0) and direction as East (We can pick any values for these). If after the given sequence of moves, we come back to (0, 0), then given sequence is circular, otherwise not. 
 
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Q2. 
K Closest Points to Origin Problem Statement
Your house is located at the origin (0,0) of a 2-D plane. There are N neighbors living at different points on the plane. Your goal is to visit exactly K neighb...read more
Ans. 
1) Consider two points with coordinates as (x1, y1) and (x2, y2) respectively. The Euclidean distance between these two points will be: 
√{(x2-x1)2 + (y2-y1)2}

2) Sort the points by distance using the Euclidean distance formula.
3) Select first K points form the list
4) Print the points obtained in any order.
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