LinkedIn Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Hard

3 DSA based questions were given to be solved within 60 minutes.

Q1. 
Optimal BST Problem Statement
You are given a sorted array representing keys of a BST and an array of frequency counts showing how often each key is searched. Your task is to construct a binary search tre...read more
Ans. 
Construct a BST with minimum search cost based on keys and frequencies.
• Create a recursive function to construct the BST by considering all possible root nodes.

• Calculate the cost for each possible BST and return the minimum total cost.

• Optimize the solution by using dynamic programming to store intermediate results.

• Ensure that the keys are sorted and frequencies are provided for each key.

• Example: For keys [1, 3, 5] and f...read more
Answered by AI
Add your answer
Q2. 
Number of Distinct Substrings Problem Statement
Given a string WORD containing lowercase English alphabets and having length N, determine the number of distinct substrings in WORD.
Input:
The first line...read more
Ans. 
Count the number of distinct substrings in a given string.
• Iterate through all possible substrings and store them in a set to avoid duplicates.

• Use nested loops to generate all substrings efficiently.

• Consider using a hash set to store unique substrings.

• Example: For input 'abcd', generate substrings 'a', 'ab', 'abc', 'abcd', 'b', 'bc', 'bcd', 'c', 'cd', 'd'.
Answered by AI
Add your answer
Q3. 
Find Distinct Palindromic Substrings
Given a string 'S', identify and print all distinct palindromic substrings within it. A palindrome reads the same forwards and backwards. For example, 'bccb' is a pali...read more
Ans. 
Find and print all distinct palindromic substrings in a given string.
• Iterate through all possible substrings of the input string.

• Check if each substring is a palindrome.

• Store distinct palindromic substrings in a set to avoid duplicates.

• Sort the set of palindromic substrings and print them space-separated.
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Medium

Technical Interview round where the interviewer asked 2 DSA problems.

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. 
Calculate the distance between two nodes in a binary tree.
• Traverse the 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 each node to the common ancestor
Answered by AI
Add your answer
Q2. 
Decode Ways Problem Statement
Given a string strNum that represents a number, the task is to determine the number of ways to decode it using the following encoding: 'A' - 1, 'B' - 2, ..., 'Z' - 26.
Input...read more
Ans. 
The task is to determine the number of ways to decode a given number string using a specific encoding.
• Use dynamic programming to solve the problem efficiently.

• Consider different cases like single digit decoding, double digit decoding, and invalid cases.

• Handle edge cases like leading zeros and empty string inputs.

• Implement a recursive function with memoization to avoid redundant calculations.
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Medium

Technical interview round where I was given 2 DSA problems to solve.

Q1. 
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.
Answered by AI
Add your answer
Q2. 
Number of Islands Problem Statement
You are given a non-empty grid that consists of only 0s and 1s. Your task is to determine the number of islands in this grid.
An island is defined as a group of 1s (re...read more
Ans. 
Count the number of islands in a grid of 0s and 1s connected horizontally, vertically, or diagonally.
• Iterate through the grid and perform depth-first search (DFS) to mark visited land cells as water.

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

• Consider all adjacent cells (horizontally, vertically, and diagonally) while exploring the island.

• Ensure to handle boundary conditions and check fo...read more
Answered by AI
Add your answer

Round duration - 30 minutes
Round difficulty - Easy

Typical HR round where he asked questions on my resume and challenges faced in my project.

Round duration - 60 minutes
Round difficulty - Easy

In first round they asked me 2 coding questions where he asked me to code as close as possible to the actual one.

Q1. 
Ninja and Sorted Array Merging Problem
Ninja is tasked with merging two given sorted integer arrays ARR1 and ARR2 of sizes 'M' and 'N', respectively, such that the merged result is a single sorted array w...read more
Ans. 
Merge two sorted arrays into one sorted array in place.
• Use two pointers to compare elements from both arrays and place them in the correct position in ARR1.

• Start from the end of ARR1 and compare elements from both arrays, placing the larger element at the end of ARR1.

• Continue this process until all elements from ARR2 are merged into ARR1.
Answered by AI
Add your answer
Q2. 
Word Distance Calculation
Given a document represented as an array/list ARR of words with length N, find the smallest distance between two given words for multiple queries. The distance is defined as the ...read more
Ans. 
Find the smallest distance between two words in a document for multiple queries.
• Iterate through the document array to find the indices of the two words in each query.

• Calculate the absolute difference between the indices to get the distance.

• If a word from the query is not present in the document, return the length of the document array.

• Repeat the process for each query and output the smallest distance for each.
Answered by AI
Add your answer

Round duration - 60 minutes
Round difficulty - Easy

Then in the second round they asked a little about tree and told me to code 2 codes.

Q1. 
Level Order Traversal Problem Statement
Given a binary tree of integers, return the level order traversal of the binary tree.
Input:
The first line contains an integer 'T', representing the number of te...read more
Ans. 
The problem requires implementing a function to return the level order traversal of a binary tree.
• Implement a function that takes the root of the binary tree as input and returns the level order traversal of the tree.

• Use a queue data structure to perform level order traversal.

• Process each level of the tree one by one, starting from the root node.

• Print the node values at each level in the order they appear from left to ...read more
Answered by AI
Add your answer
Q2. 
Combination Sum Problem Statement
Given an array of distinct positive integers ARR and a non-negative integer 'B', find all unique combinations in the array where the sum is equal to 'B'. Numbers can be c...read more
Ans. 
Find all unique combinations in an array where the sum is equal to a given target sum, with elements in non-decreasing order.
• Use backtracking to generate all possible combinations.

• Sort the array to ensure elements are in non-decreasing order.

• Track the current combination and sum while backtracking.

• Terminate recursion when the sum equals the target sum.

• Avoid duplicates by skipping elements that have been used in previou
Answered by AI
Add your answer

Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.