Flipkart Software Engineer Interview Questions and Answers

Round duration - 120 minutes
Round difficulty - Medium

Q1. 
Find All Pairs Adding Up to Target
Given an array of integers ARR of length N and an integer Target, your task is to return all pairs of elements such that they add up to the Target.
Input:
The first line ...read more
Ans. 
Given an array of integers and a target, find all pairs of elements that add up to the target.
• Iterate through the array and for each element, check if the target minus the element exists in a hash set.

• If it exists, add the pair to the result. If not, add the element to the hash set.

• Handle cases where the same element is used twice in a pair.

• Return (-1, -1) if no pair is found.
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Q2. 
Clone a Linked List with Random Pointers
Given a linked list where each node contains two pointers: one pointing to the next node and another random pointer that can point to any node within the list (or ...read more
Ans. 
Create a deep copy of a linked list with random pointers.
• Iterate through the original linked list and create a new node for each node in the list.

• Store the mapping of original nodes to new nodes in a hashmap to handle random pointers.

• Update the random pointers of new nodes based on the mapping stored in the hashmap.

• Return the head of the copied linked list.
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Unique Element in Array
Given an arbitrary array arr consisting of N non-negative integers where every element appears thrice except for one. Your task is to find the element in the array that appears onl...read more
Ans. 
Find the element that appears only once in an array where every other element appears thrice.
• Use bitwise operations like XOR to find the unique element in linear time complexity.

• XOR all elements in the array, the result will be the unique element.

• Elements that appear thrice will cancel out each other in XOR operation.

• Example: arr = [2, 2, 3, 2], XOR of all elements = 3 which is the unique element.
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Q2. 
Next Greater Element Problem Statement
You are provided with an array or list ARR containing N positive integers. Your task is to determine the Next Greater Element (NGE) for each element in the array.
T...read more
Ans. 
Find the Next Greater Element for each element in an array.
• Iterate through the array from right to left

• Use a stack to keep track of elements with no greater element to the right

• Pop elements from the stack until a greater element is found or stack is empty
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Convert BST to Greater Sum Tree
Given a Binary Search Tree (BST) of integers, your task is to convert it into a greater sum tree. In the greater sum tree, each node's value should be replaced with the sum...read more
Ans. 
Convert a Binary Search Tree into a Greater Sum Tree by replacing each node's value with the sum of all nodes' values greater than the current node's value.
• Traverse the BST in reverse inorder (right, root, left) to visit nodes in descending order.

• Keep track of the running sum of visited nodes' values and update each node's value with this sum.

• Recursively apply the above steps to all nodes in the BST.

• Example: For input ...read more
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Q2. 
Sort Linked List Problem Statement
You are given a linked list of N nodes where each node contains values 0, 1, and 2 exclusively. Your task is to sort the linked list.
Input:
The first line contains an...read more
Ans. 
Sort a linked list containing values 0, 1, and 2 exclusively.
• Use three pointers to keep track of nodes with values 0, 1, and 2 separately.

• Traverse the linked list and move nodes to their respective positions based on their values.

• Finally, concatenate the three lists in the order 0 -> 1 -> 2 to get the sorted linked list.
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Round duration - 45 minutes
Round difficulty - Medium

Q1. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
Ans. 
Count the number of islands in a 2D matrix of 1s and 0s.
• Use Depth First Search (DFS) or Breadth First Search (BFS) to traverse the matrix and identify connected groups of 1s.

• Maintain a visited array to keep track of visited cells to avoid redundant traversal.

• Increment the island count each time a new island is encountered.

• Consider edge cases like when the matrix is empty or when all cells are water (0s).
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Q2. 
Maximum Path Sum in a Matrix
Given an N*M matrix filled with integer numbers, determine the maximum sum that can be obtained from a path starting from any cell in the first row to any cell in the last row...read more
Ans. 
Find the maximum sum that can be obtained from a path in a matrix from the first row to the last row.
• Use dynamic programming to keep track of the maximum sum at each cell.

• Consider moving down, down-left, and down-right to calculate the maximum sum.

• Start from the second row and update the values based on the maximum sum from the row above.

• At the end, find the maximum sum in the last row to get the final result.
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