LinkedIn Software Developer Intern Interview Questions, Process, and Tips

Round duration - 120 minutes
Round difficulty - Medium

10 min for debugging
40 min for problems(coding)
40 min for pyschometric
30 min for aptitude

Q1. 
Total Unique Paths Problem Statement
You are located at point ‘A’, the top-left corner of an M x N matrix, and your target is point ‘B’, the bottom-right corner of the same matrix. Your task is to calcula...read more
Ans. 
The task is to calculate the total number of unique paths from the top-left to bottom-right corner of an M x N matrix by moving only right or down.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the number of unique paths for each cell in the matrix.

• Initialize the first row and first column with 1 as there is only one way to reach each cell in the first row and column.

• For each cell ...read more
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Q2. 
Most Frequent Word Problem Statement
You are given two strings 'A' and 'B' composed of words separated by spaces. Your task is to determine the most frequent and lexicographically smallest word in string ...read more
Ans. 
Find the most frequent and lexicographically smallest word in string 'A' that is not present in string 'B'.
• Split strings 'A' and 'B' into words

• Count frequency of each word in 'A'

• Check if word is not in 'B' and is the most frequent and lexicographically smallest

• Return the word or -1 if no such word exists
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Round duration - 90 Minutes
Round difficulty - Easy

timing was 4 pm . we connected on amazon chime. Initially he asked me a few things from resume then moved on to problem solving.

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 all eight possible directions for connectivity while traversing the matrix.

• Handle edge ca...read more
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Q2. 
Largest Rectangle in Histogram Problem Statement
You are given an array/list HEIGHTS of length N, where each element represents the height of a histogram bar. The width of each bar is considered to be 1.
...read more
Ans. 
Find the area of the largest rectangle that can be formed within the bounds of a given histogram.
• Iterate through the histogram bars and maintain a stack to keep track of increasing heights.

• Calculate the area of the rectangle formed by each bar as the smallest height in the stack times the width.

• Update the maximum area found so far and return it as the result.
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E-commerce

Round duration - 60 minutes
Round difficulty - Easy

There was 2 coding questions
Based on ds and algorithms

Q1. 
Ninja's Pattern with Powers of 2
Ninja, who loves playing with numbers, sets out to arrange numbers within 'N' rows. The unique arrangement follows these rules: the first row contains 1 number, the second...read more
Ans. 
Generate a pattern of numbers in rows following a specific sequence based on powers of 2.
• Start with 1 number in the first row, 2 numbers in the second row, 4 numbers in the third row, and so on based on powers of 2.

• Fill the pattern with numbers in increasing sequence from 1 to 9, recycling back to 1 after reaching 9.

• Output the pattern for a given number 'N' of rows.

• Example: For N = 4, the pattern would be 1, 23, 4567,
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Q2. 
Validate Binary Search Tree (BST)
You are given a binary tree with 'N' integer nodes. Your task is to determine whether this binary tree is a Binary Search Tree (BST).
BST Definition:
A Binary Search Tr...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.

• Example: For a node with data 4, left subtree nodes (2, 1, 3) are smaller and righ
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Round duration - 60 minutes
Round difficulty - Easy

There was 2 coding questions based on ds and algorithms

Q1. 
Zig-Zag Array Rearrangement
You are provided with an array of distinct elements, and your task is to rearrange the array elements in a zig-zag manner. Specifically, for every odd index i, the element ARR[...read more
Ans. 
Rearrange array elements in a zig-zag manner where every odd index element is greater than its neighbors.
• Iterate through the array and swap elements to satisfy the zig-zag condition.

• Ensure that for every odd index i, ARR[i] > ARR[i-1] and ARR[i] > ARR[i+1].

• Multiple correct answers may exist for a given array.
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Q2. 
Flatten a Linked List
You are provided with a linked list of 'N' nodes. Each node contains two pointers: NEXT, pointing to the next node in the list, and CHILD, pointing to a linked list. Each child linke...read more
Ans. 
Flatten a linked list of sorted child linked lists into a single sorted linked list.
• Traverse the linked list and maintain a priority queue to keep track of the next smallest element.

• Merge the child linked lists into the priority queue while traversing the main linked list.

• Pop elements from the priority queue to create the final flattened linked list.
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Round duration - 45 Minutes
Round difficulty - Medium

My interview started at 9:30 and it took around 45 minutes to complete my interview.This was held on Amazon Chime and the interview lasted for 1 hour. Firstly the interviewer asked to introduce about myself, later asked regarding the projects I have mentioned in my resume. Then started displaying the coding question. The first question is number of islands in a matrix.

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 all cells are water (0s).
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Round duration - 2 hour 30 mins
Round difficulty - Easy

Debugging: This section had 7 debugging problems, which consist of code snippets that have some logical error that needs to be rectified.
Reasoning Ability: This section consists of some verbal reasoning questions and some aptitude questions.
Coding: This section consists of 2 coding problems.

Q1. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. 
Given a sorted N * N matrix, find the position of a target integer X within the matrix.
• Iterate over each row and column to search for the target integer X

• Utilize the sorted nature of the matrix to optimize the search process

• Return the position of X if found, else return -1 -1
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Q2. 
Clone Linked List with Random Pointer Problem Statement
Given a linked list where each node has two pointers: one pointing to the next node and another which can point randomly to any node in the list or ...read more
Ans. 
Cloning a linked list with random pointers by creating new nodes rather than copying references.
• Create a deep copy of the linked list by iterating through the original list and creating new nodes with the same values.

• Update the random pointers of the new nodes by mapping the original node's random pointer index to the corresponding new node.

• Ensure the cloned linked list is an exact copy of the original by validating th...read more
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Round duration - 60 minutes
Round difficulty - Medium

Around 30 candidates were shortlisted from my campus and over 150+ candidates were shortlisted from the university, and I was one of them. Then my first round of interviews was scheduled. I was pretty nervous before the interview.

Q1. 
Return in Row Wave Form Problem Statement
You are provided with a 2D array having dimensions 'N*M'. Your task is to traverse the elements row-wise and return a single-dimensional array which stores these ...read more
Ans. 
Traverse a 2D array row-wise and return elements in a wave pattern.
• Traverse the 2D array row-wise and store elements alternately in a wave pattern.

• For each row, store elements from left to right for odd rows and from right to left for even rows.

• Return the final 1D array representing the wave pattern of elements.
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Q2. 
Strict Binary Tree Construction
Given two lists, one representing the preorder traversal ('PRE') of a strict binary tree and the other ('TYPENL') indicating if each node is a leaf ('L') or non-leaf ('N')....read more
Ans. 
Construct a strict binary tree from preorder traversal and leaf/non-leaf indicators.
• Create a binary tree node class with value and left/right pointers.

• Use a stack to keep track of parent nodes while constructing the tree.

• Check if the current node is a leaf or non-leaf based on 'TYPENL' list.
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Round duration - 60 minutes
Round difficulty - Medium

My interviewer introduced himself in the beginning and asked for my introduction.

Q1. 
Alien Dictionary Problem Statement
You've been provided with a sorted dictionary in an alien language. Your task is to determine the character order of this alien language from this dictionary. The dictio...read more
Ans. 
Given a sorted dictionary in an alien language, determine the character order of the language.
• Iterate through the dictionary to find the order of characters based on their appearance in words.

• Create a graph of characters and their relationships based on adjacent words in the dictionary.

• Perform a topological sort on the graph to determine the character order.

• Return the list of characters in the correct order as the outp
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Round duration - 90 minutes
Round difficulty - Medium

25 mcqs and 2 coding questions
(It was a part of Amazewow process via Amazewit https://www.amazewit.in/)
Timing- any time between 22-24 may 2020
Webcam was on.

Q1. 
Longest Decreasing Subsequence Problem Statement
Given an array/list of integers ARR consisting of N integers, your task is to determine the length of the longest decreasing subsequence.
Explanation:
A ...read more
Ans. 
Find the length of the longest decreasing subsequence in an array of integers.
• Use dynamic programming to keep track of the longest decreasing subsequence ending at each index.

• Initialize an array to store the length of the longest decreasing subsequence ending at each index.

• Iterate through the array and update the length of the longest decreasing subsequence for each element.

• Return the maximum value in the array as the
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Q2. 
Next Greater Element Problem Statement
Given an array arr of length N, your task is to compute the Next Greater Element (NGE) for each element in the array. The NGE for an element X is the first greater e...read more
Ans. 
The task is to find the Next Greater Element (NGE) for each element in an array.
• Iterate through the array from right to left and use a stack to keep track of elements.

• For each element, pop elements from the stack until finding a greater element.

• Store the next greater element in a result array, if no greater element is found, store -1.

• Time complexity can be optimized to O(N) using a stack.

• Example: For input array [1, 3,
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Round duration - 60 minutes
Round difficulty - Medium

It held at morning 10 AM.
The interviewer was very friendly.
I was asked to solve 2 coding questions and was continuously provided with hints by the interviewer.
Question was on Array and Trees.

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

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

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

• Example: For the given BST, the transform...read more
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Round duration - 45 minutes
Round difficulty - Hard

Morning 8 AM.
The interviewer was very friendly provided with various hints.
It was covering complex coding questions on Tree Data Structures.

Q1. 
Time to Burn Tree Problem
You are given a binary tree consisting of 'N' unique nodes and a start node where the burning will commence. The task is to calculate the time in minutes required to completely b...read more
Ans. 
Calculate the time in minutes required to completely burn a binary tree starting from a given node.
• Perform a depth-first search (DFS) to calculate the time taken to burn the entire tree.

• Track the time taken for each node to catch fire and propagate the fire to its adjacent nodes.

• Return the maximum time taken among all nodes as the total time to burn the entire tree.
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Q2. 
Binary Tree Node Distance Problem Statement
Given a binary tree and the values of two nodes, your task is to find the distance between these nodes within the Binary Tree.
Distance is defined as the minim...read more
Ans. 
Find the distance between two nodes in a binary tree.
• Traverse the binary tree to find the paths from the root to each node.

• Find the lowest common ancestor of the two nodes.

• Calculate the distance by adding the distances from the nodes to the common ancestor.
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Round duration - 90 minutes
Round difficulty - Medium

It contains 20 MCQs, based on the output of the given code and next followed by 2 programming questions. To get qualified for the next round you need to solve the 2 programming questions completely. The next rounds will be interviews. They had given 3 days time to attempt the first round.

Q1. 
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 path in a matrix from top row to bottom row by moving down or diagonally.
• Use dynamic programming to keep track of maximum sum at each cell.

• At each cell, the maximum sum is the current cell value plus the maximum of the three possible previous cells.

• Iterate through the matrix row by row and update the maximum sum at each cell.

• Return the maximum sum found in the last row as the result.
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Q2. 
Dice Throws Problem Statement
You are given D dice, each having F faces numbered from 1 to F. The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up num...read more
Ans. 
The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up numbers equals the given 'target' sum.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the number of ways to reach each sum with each dice.

• Iterate through the dice and sum values to fill up the array.

• Return the result modulo 10^9 + 7.

• Optimize the solution to use no more than O(S)
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Round duration - 50 minutes
Round difficulty - Hard

Q1. 
Palindrome Permutation - Problem Statement
Determine if a permutation of a given string S can form a palindrome.
Example:
Input:
string S = "aab"
Output:
"True"
Explanation:
The permutation "aba" o...read more
Ans. 
Check if a permutation of a string can form a palindrome.
• Create a frequency map of characters in the string.

• Count the number of characters with odd frequencies.

• If there is at most one character with an odd frequency, the string can form a palindrome.
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Q2. 
Longest Common Subsequence Problem Statement
Given two strings STR1 and STR2, determine the length of their longest common subsequence.
A subsequence is a sequence that can be derived from another sequen...read more
Ans. 
The problem involves finding the length of the longest common subsequence between two given strings.
• Implement a function to find the longest common subsequence length between two strings.

• Use dynamic programming to solve the problem efficiently.

• Iterate through the strings and build a matrix to store the lengths of common subsequences.

• Return the value in the bottom-right cell of the matrix as the result.
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