LinkedIn Senior Software Engineer Interview Questions and Answers

Algorithm to find 2 numbers in an array whose sum is equal to a target integer

• Use a hash table to store the difference between target and each element in the array

• Iterate through the array and check if the current element exists in the hash table

• Return the pair of elements that sum up to the target integer

Write a select statement to retrieve work of all users who belong to my team.

• Join USERS and WORK tables on user_id

• Join MANAGERS and USERS tables on team

• Filter by manager_id

The manifest.json file contains the most important information of a Chrome extension.

• The manifest.json file includes the version number, permissions, content scripts, background scripts, and other important details.

• It is located in the root directory of the extension.

• It is required for all Chrome extensions.

• Example: "manifest_version": 2, "version": "1.0", "permissions": ["tabs", "storage"]

Hashtable is faster for finding an item than a sorted list.

• Hashtable has constant time complexity O(1) for finding an item.

• Sorted list has logarithmic time complexity O(log n) for finding an item.

• Hashtable uses hashing to directly access the item's location.

• Sorted list requires binary search to find the item's location.

• Hashtable is ideal for large datasets with frequent lookups.

• Sorted list is ideal for datasets that re

JSON and XML are the most popular data interchange formats when using APIs.

• JSON (JavaScript Object Notation) is a lightweight format that is easy to read and write. It is widely used in web APIs.

• XML (Extensible Markup Language) is a more complex format that is also widely used in web APIs.

• Other formats include CSV (Comma Separated Values), YAML (YAML Ain't Markup Language), and Protocol Buffers.

Popular APIs for Social Commerce services

• Facebook Graph API for social media integration

• Instagram API for photo sharing and tagging

• Twitter API for real-time updates and customer engagement

• Pinterest API for product discovery and sharing

• Google Maps API for location-based services

• PayPal API for secure payment processing

Use a script to iterate through each HTML page, locate phone numbers, and update their format.

• Write a script using a programming language like Python or JavaScript to iterate through each HTML page

• Use regular expressions to locate phone numbers in the pages

• Update the format of the phone numbers as needed (e.g. adding country code, changing separators)

• Save the updated HTML pages with the new phone number format

Designing Google Suggest system

• I would start by analyzing user search patterns and frequently searched keywords

• Then, I would create a database of these keywords and their associated search results

• I would use indexing services to quickly retrieve relevant results for each keyword

• I would also implement machine learning algorithms to improve the accuracy of suggestions over time

Check if a number is a power of 2 and odd.

• To check if a number is a power of 2, use bitwise AND operator with the number and its predecessor. If the result is 0, it is a power of 2.

• To check if a number is odd, use modulus operator with 2. If the result is 1, it is odd.

• Example code in Python:

• def is_power_of_two(num):

• return num & (num - 1) == 0

• def is_odd(num):

• return num % 2 == 1

By introducing new menu items, optimizing pricing strategy, and improving the overall dining experience.

• Conduct a survey to understand the preferences of employees

• Introduce healthy and affordable meal options

• Offer discounts for bulk orders or loyalty programs

• Partner with local vendors to source fresh ingredients

• Improve the ambiance and seating arrangements

• Implement online ordering and delivery services

Reviewing 30 million ads from 42 languages in Google AdWords and rejecting non-compliant ads requires a systematic approach.

• Create a set of specific rules and guidelines for ad compliance

• Use automated tools to filter out ads that violate the rules

• Assign a team of reviewers to manually check the remaining ads

• Ensure that the reviewers are fluent in the languages of the ads they are reviewing

• Regularly update the rules and...read more

A generic swap function swaps two values of any data type.

• The function should take two parameters of any data type.

• Use a temporary variable to store the value of one parameter.

• Assign the value of the second parameter to the first parameter.

• Assign the value of the temporary variable to the second parameter.

Search for an element in a rotated sorted linked list.

• Find the pivot point where the list is rotated.

• Divide the list into two sublists based on the pivot point.

• Perform binary search on the appropriate sublist.

• Handle edge cases such as empty list and list with only one element.

Search an element in a rotated sorted array

• Find the pivot point where the array is rotated

• Divide the array into two sub-arrays based on pivot point

• Perform binary search on the appropriate sub-array

• Repeat until element is found or sub-array size is 1

Find 5 missing numbers in an array of size 95 containing numbers in range 1 to 100.

• Create a boolean array of size 100 and mark the present numbers

• Iterate through the boolean array and find the missing numbers

• Alternatively, use a HashSet to store the present numbers and find the missing ones

Given a Sudoku board, find possible numbers for an empty cell.

• Iterate through empty cells and check possible numbers using row, column, and box constraints.

• Use a set to keep track of possible numbers for each empty cell.

• Return the set of possible numbers for the given empty cell.

Find integer average of 4 unsigned integers without typecasting

• Add all the integers and divide by 4

• Use bit shifting to divide by 4

• Handle overflow by using long long data type

• Use unsigned int data type for input

Code to identify 32 bit or 64 bit architecture of a processor

• Check if the operating system is 32 bit or 64 bit

• If OS is 32 bit, processor is 32 bit

• If OS is 64 bit, check if processor supports 64 bit architecture

• Use CPUID instruction to check if processor supports 64 bit architecture

Convert binary number to base 64 integer

• Divide the binary number into groups of 6 bits

• Convert each group of 6 bits to decimal

• Map the decimal value to the corresponding base 64 character

• Concatenate the base 64 characters to form the final integer

Multiple data structures are used to print nodes in a specific order. One data structure cannot be used alone.

• The given order suggests a depth-first search traversal of a tree-like structure.

• A stack can be used to keep track of the nodes to be visited.

• A queue can be used to store the children of a node in the order they are visited.

• An array can be used to store the nodes in the required order.

• A linked list can be used ...read more

Find largest pen using minimum comparisons with tops.

• Divide pens into two groups and compare largest pen from each group with largest top.

• Repeat the process with the group containing the largest pen until only one pen is left.

• The remaining pen is the largest pen.

• Total number of comparisons required is 2n-3.

Given n dice with 'a' sides and sum b, return no. of ways to obtain b. Optimize time and space complexity.

• Use dynamic programming to reduce time complexity

• Create a 2D array to store the number of ways to obtain each sum for each number of dice

• Use rolling arrays to optimize space complexity

• Example: n=2, a=6, b=7 -> 6 ways to obtain sum 7

• Example: n=3, a=4, b=8 -> 21 ways to obtain sum 8

Sort 128 GB data on 2 machines with 64 GB RAM each. Extend to 1000 machines.

• Use external sorting algorithm like merge sort or quick sort

• Divide data into smaller chunks and sort them individually

• Merge sorted chunks using additional RAM

• For 1000 machines, use distributed sorting algorithms like MapReduce or Hadoop

• Ensure data consistency and fault tolerance in distributed sorting

To determine if a point is inside a polygon, use the ray casting algorithm.

• Create a line from the point to a point outside the polygon

• Count the number of times the line intersects with the polygon edges

• If the count is odd, the point is inside the polygon; otherwise, it is outside

The four storage classes in C are auto, register, static, and extern.

• Auto: default storage class for all local variables

• Register: used to define local variables that should be stored in a register instead of RAM

• Static: used to define local variables that retain their value between function calls

• Extern: used to declare a global variable that is defined in another file

i is stored in global data segment, j is stored in stack, k is stored in heap.

• i is a global variable and is stored in the global data segment

• j is a local variable and is stored in the stack

• k is a pointer variable and is stored in the stack, while the memory it points to is allocated on the heap using malloc()

Use a hash table to store the words and check for existence in constant time.

• Create a hash table with the words as keys and a boolean value as the value.

• For each new word, check if it exists in the hash table. If it does, it has appeared before. If not, add it to the hash table.

• Alternatively, use a set data structure to store only the unique words and check for existence in the set.

Operating on images in parallel involves dividing the image into smaller parts and processing them simultaneously.

• Divide the image into smaller parts using techniques like tiling or splitting

• Use parallel processing techniques like multi-threading or GPU acceleration

• Combine the processed parts to form the final image

• Examples: image segmentation, object detection, image enhancement

Hardware engines support parallelism through multiple cores and threads.

• Hardware engines can have multiple cores and threads to execute tasks simultaneously.

• Parallelism can improve performance and efficiency in hardware-based tasks.

• Examples include GPUs, FPGAs, and ASICs that have parallel processing capabilities.

• Hardware parallelism can also be achieved through distributed computing and clustering.

• Programming language...read more

Modern OSes support parallelism through multi-core processors and threading.

• Modern OSes like Windows, macOS, and Linux support parallelism through multi-core processors and threading.

• Parallelism can be achieved through processes or threads.

• Parallelism can improve performance and efficiency of software.

• Examples of parallel programming frameworks include OpenMP and MPI.

Memory protection is a feature of an operating system that prevents unauthorized access to memory locations.

• Memory protection is achieved through the use of memory management units (MMUs) and virtual memory.

• MMUs map virtual addresses to physical addresses and enforce access permissions.

• Virtual memory allows the OS to allocate memory to processes in a way that isolates them from each other.

• Examples of memory protection ...read more

To speed up multiplication of small integers in an array, we can use bitwise operations and parallel processing.

• Use bitwise operations like shifting and ANDing to perform multiplication faster.

• Divide the array into smaller chunks and perform multiplication in parallel using multi-threading or SIMD instructions.

• Use lookup tables for frequently used values to avoid repeated calculations.

• Use compiler optimizations like lo...read more

Design a data structure for excel spreadsheet

• Use a 2D array to store cell values

• Implement formulas using a stack

• Include formatting options for cells

Insertion sort and quicksort are sorting algorithms used to sort arrays of data.

• Insertion sort: iterates through the array and inserts each element into its proper position.

• Quicksort: selects a pivot element and partitions the array into two sub-arrays, one with elements less than the pivot and one with elements greater than the pivot.

• Insertion sort is best for small arrays, while quicksort is best for large arrays.

• Bot...read more

Merge two sorted linked lists using recursion

• Create a recursive function that compares the first nodes of both lists

• Set the smaller node as the head of the merged list and call the function again with the next node of the smaller list

• Base case: if one list is empty, return the other list

• Return the merged list

Given an integer, determine which byte is zero.

• Convert the integer to a byte array using bitwise operations.

• Iterate through the byte array and check for a zero value.

• Return the index of the zero byte.

• Consider endianness when converting to byte array.

To check endianness, create a 4-byte integer with a known value and check the byte order.

• Create a 4-byte integer with a known value

• Check the value of the first byte to determine endianness

• If the first byte is the least significant, the machine is little endian

• If the first byte is the most significant, the machine is big endian

Static objects can be used to print something before main() execution.

• Static objects are initialized before main() execution

• They can be used to print something before main()

• Example: static int x = printf("Hello World!");

• Output: Hello World! will be printed before main() execution

Static variables are allocated memory in the data segment of the program's memory space.

• Static variables have a fixed memory location throughout the program's execution.

• They are initialized to zero by default.

• If initialized explicitly, they are stored in the data segment.

• Static variables can be accessed by any function in the program.

Finding space and time complexity of a recursive function.

• Space complexity is the amount of memory used by the function.

• Time complexity is the amount of time taken by the function to execute.

• Recursive functions have higher space complexity due to the call stack.

• Time complexity can be calculated using Big O notation.

• Examples of recursive functions include factorial and Fibonacci sequence.

Diamond hierarchy problem is a problem in object-oriented programming where a class inherits from multiple classes in a diamond-shaped hierarchy.

• Occurs when a class inherits from two classes that share a common base class

• Can lead to ambiguity in method calls and data members

• Solved using virtual inheritance or by using interfaces