Goldman Sachs Software Analyst Interview Questions, Process, and Tips

Q1. Difference between SQL and NoSQL
Ans. 
SQL is a traditional relational database management system, while NoSQL is a non-relational database system.
• SQL is structured, uses tables with predefined schema, and is good for complex queries.

• NoSQL is unstructured, uses collections or documents, and is good for large amounts of data with simple queries.

• SQL is ACID compliant, ensuring data integrity, while NoSQL is BASE (Basically Available, Soft state, Eventually co...read more
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Q2. Reverse a linked list recursively
Ans. 
Reverse a linked list recursively by swapping pointers
• Start by checking if the current node is null or the next node is null

• If so, return the current node as it is the new head of the reversed list

• Otherwise, recursively call the function on the next node and swap pointers
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Q3. Implement a min stack
Ans. 
A min stack is a stack data structure that supports the usual push and pop operations, along with an additional operation to retrieve the minimum element in constant time.
• Create a stack to store the elements and another stack to store the minimum values encountered so far.

• When pushing an element, check if it is smaller than the current minimum. If so, push it onto the minimum stack.

• When popping an element, check if it ...read more
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Q4. Implement two stacks in a single array
Ans. 
Implement two stacks in a single array using two different approaches
• Divide the array into two halves and use one half for each stack

• Use two pointers, one for each stack, and move them towards each other as elements are pushed or popped

• Consider edge cases like stack overflow and underflow
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Q5. Was asked to write an sql query involing group by and joins
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Round duration - 120 minutes
Round difficulty - Medium

This round was held in the evening at 6 o'clock on Hackerrank. It had coding questions: easy, medium, and hard level and MCQ's ( 1 minute for each MCQ). Negative marking was also there.

Q1. 
Word Search Problem Statement
Given a two-dimensional grid of size N x M consisting of upper case characters and a string 'WORD', determine how many times the 'WORD' appears in the grid.
The 'WORD' can b...read more
Ans. 
Count the number of occurrences of a given word in a 2D grid by moving in all eight possible directions.
• Iterate through each cell in the grid and start searching for the word from that cell in all eight directions.

• Keep track of the number of occurrences found while searching.

• Handle edge cases like word length exceeding grid dimensions or starting from out-of-bounds cells.
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Q2. 
Climbing the Leaderboard Problem Statement
In a game leaderboard, scores determine rankings where the highest score gets rank 1. Players with identical scores share the same rank, followed by the next ran...read more
Ans. 
The task is to determine a player's leaderboard rank for each game score based on given leaderboard and game scores.
• Iterate through each game score and compare it with leaderboard scores to determine the rank.

• Use a hashmap to store the leaderboard scores and their corresponding ranks.

• Handle cases where multiple players have the same score and share the same rank.

• Return an array of ranks for each game score.
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Round duration - 40 minutes
Round difficulty - Medium

This was an interview round ( technical round) that was held on video-call and a coding platform was also shared. The interviewer was very friendly with me . She was praising me on every solution that I provided.

Q1. 
Flatten the Multi-Level Linked List Problem
You are provided with a multi-level linked list consisting of 'N' nodes. Each node contains a 'next' and 'child' pointer that may point to another node. Your ta...read more
Ans. 
The task is to flatten a multi-level linked list into a singly linked list and return the head of the modified linked list.
• Traverse the linked list and keep track of nodes with child pointers

• Flatten the child linked list and merge it with the main linked list

• Update the 'next' pointers to create a singly linked list

• Return the head of the modified linked list
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Round duration - 40 minutes
Round difficulty - Medium

This was an interview round ( technical round) that was held on video-call and a coding platform was also shared. The interviewer was very friendly with me . She was praising me on every solution that I provided.

Q1. 
Design a HashSet
Create a HashSet data structure without using any built-in hash table libraries.
Functions Description:
1) Constructor: Initializes the data members as required.

2) add(value): Inserts...read more
Ans. 
Design a HashSet data structure with add, contains, and remove functions.
• Implement a HashSet using an array and handling collisions using chaining or open addressing.

• Use a hash function to map values to indices in the array.

• For add function, insert the value at the hashed index.

• For contains function, check if the value exists at the hashed index.

• For remove function, delete the value at the hashed index and return it, o
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Round duration - 40 minutes
Round difficulty - Medium

It was online HR+Technical Round .

Q1. 
Print Nodes at Distance K from a Given Node
Given an arbitrary binary tree, a node of the tree, and an integer 'K', find all nodes that are at a distance K from the specified node, and return a list of th...read more
Ans. 
Given a binary tree, a target node, and an integer K, find all nodes at distance K from the target node.
• Traverse the binary tree to find the target node.

• Use BFS to traverse the tree from the target node to nodes at distance K.

• Keep track of the distance while traversing the tree.

• Return the values of nodes at distance K in any order.
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Round duration - 135 minutes
Round difficulty - Medium

The round consisted of 5 sections. The Coding section had 2 questions, CS mutiple choice section had 8 MCQs, Problem solving multiple choice section had 7 MCQs, Advanced section had 1 programming question and the Subjective section had 2 questions. Each MCQ earned 5 marks for correct answer and -2 for incorrect answer.

Q1. 
Word Search Problem Statement
Given a two-dimensional grid of size N x M consisting of upper case characters and a string 'WORD', determine how many times the 'WORD' appears in the grid.
The 'WORD' can b...read more
Ans. 
Count the number of occurrences of a given word in a 2D grid by moving in all possible directions.
• Iterate through each cell in the grid and start searching for the word from that cell in all eight directions.

• Keep track of the number of occurrences found while searching.

• Handle edge cases like word length exceeding grid dimensions or starting from out-of-bounds cells.
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Q2. 
Climbing the Leaderboard Problem Statement
In a game leaderboard, scores determine rankings where the highest score gets rank 1. Players with identical scores share the same rank, followed by the next ran...read more
Ans. 
The task is to determine a player's leaderboard rank for each game score based on given leaderboard and game scores.
• Iterate through each game score and compare it with leaderboard scores to determine the rank.

• Use a hashmap to store the leaderboard scores and their corresponding ranks.

• Handle cases where multiple players have the same score and rank accordingly.
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Round duration - 30 minutes
Round difficulty - Easy

This was a technical round held over the zoom video call around 11:00 hours. I was given a code-pair link where I had to code. The interview started with the question - "Tell me about yourself." Then, he asked the subjects I studied and asked few things about data structures and algorithms. He asked my preferred language of coding and gave two coding problems to solve. Finally, he asked me to explain my project and then gave me a scenario where he extended the project and asked about my design and database approach for that case.

Q1. 
Partition to K Equal Sum Subsets Problem
Given an array of integers and a positive integer 'K', determine if it is possible to divide the array into 'K' non-empty subsets such that the sum of elements in ...read more
Ans. 
The problem involves dividing an array into K subsets with equal sum.
• Use backtracking to try all possible combinations of dividing the array into K subsets.

• Keep track of the sum of elements in each subset and check if they are equal to the target sum.

• Optimize the backtracking algorithm by pruning branches that cannot lead to a valid solution.

• Consider edge cases such as empty array, negative numbers, and unequal divisio...read more
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Q2. 
Partition Set Into Two Subsets With Minimum Difference
Given an array of N non-negative integers, split the array into two subsets such that the absolute difference between their sums is minimized.
The t...read more
Ans. 
Split array into two subsets with minimum absolute difference between their sums.
• Use dynamic programming to find the minimum absolute difference between the sums of two subsets.

• Iterate through all possible sums of subsets and find the minimum difference.

• Consider each element either being included in the first subset or the second subset.

• Keep track of the minimum absolute difference found so far.

• Return the minimum absol...read more
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Round duration - 20 minutes
Round difficulty - Easy

This was also a technical round held over the zoom video call around 14:00 hours. In this round also, I was given a code-pair link where I had to code. First of all, he asked me to introduce myself. Then, he asked about tree data structure and its practical implementation. Then, he gave me two coding questions to code. At last, he asked about the operating systems, i.e., Windows, Linux and have I ever installed Linux in my system by deleting Windows.

Q1. 
Prime Numbers Identification
Given a positive integer N, your task is to identify all prime numbers less than or equal to N.
Explanation:
A prime number is a natural number greater than 1 that has no po...read more
Ans. 
Identify all prime numbers less than or equal to a given positive integer N.
• Iterate from 2 to N and check if each number is prime

• Use the Sieve of Eratosthenes algorithm for efficient prime number identification

• Optimize by only checking up to the square root of N for divisors
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Q2. 
Find Pairs in a Doubly-Linked List
A sorted doubly-linked list of distinct positive integers is provided, along with an integer 'X'. Your task is to identify and print all unique pairs from the list whose...read more
Ans. 
Find pairs in a sorted doubly-linked list whose sum equals a given integer 'X'.
• Traverse the list from both ends to find pairs with sum equal to 'X'.

• Use two pointers approach to efficiently find the pairs.

• Handle cases where the sum is less than, equal to, or greater than 'X'.
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Round duration - 90 Minutes
Round difficulty - Medium

Timing: Evening around 5
The test was set up inside the computer centre and library of our institute.
There were people from GS and also from hackerrank who were conducting the test.
The test had mcqs + coding questions + essay writing.
Overall the paper I found was medium

Q1. 
Next Greater Number Problem Statement
Given a string S which represents a number, determine the smallest number strictly greater than the original number composed of the same digits. Each digit's frequenc...read more
Ans. 
The task is to find the smallest number greater than the given number, using the same set of digits.
• Iterate from right to left to find the first digit that can be swapped with a smaller digit on its right.

• Swap this digit with the smallest digit on its right that is greater than it.

• Sort the digits to the right of the swapped digit in ascending order to get the smallest number.

• If no such digit is found, return -1.

• Example
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Q2. 
Rat in a Maze Problem Statement
You need to determine all possible paths for a rat starting at position (0, 0) in a square maze to reach its destination at (N-1, N-1). The maze is represented as an N*N ma...read more
Ans. 
The task is to find all possible paths for a rat to navigate through a maze from start to finish.
• Use backtracking algorithm to explore all possible paths in the maze.

• Keep track of visited cells to avoid infinite loops.

• Generate paths by moving in all possible directions (up, down, left, right) until reaching the destination.

• Return the list of valid paths sorted in alphabetical order.
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Q3. 
Fenwick Tree Problem Statement
You are provided with an array/list ARR consisting of 'N' integers, along with 'Q' queries. Each query can be of one of the following two types:
• Type 1 (Range Sum): Give...read more
Ans. 
The problem involves executing range sum and point update queries on an array using Fenwick Tree data structure.
• Use Fenwick Tree to efficiently handle range sum and point update queries.

• For range sum queries, calculate prefix sums and use them to compute the sum in the given range.

• For point update queries, update the Fenwick Tree accordingly to reflect the changes in the array.

• Ensure to handle the queries efficiently t...read more
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Round duration - 90 Miinutes
Round difficulty - Easy

The round included discussion over my resume and the projects I had made. Along with that, the person was fascinated by the co-curricular so he went on asking about those. 
Finally we started discussing data structures and algorithm.

Q1. 
Maximum Subarray Sum Problem Statement
Given an array arr of length N consisting of integers, find the sum of the subarray (including empty subarray) with the maximum sum among all subarrays.
Explanation...read more
Ans. 
Find the sum of the subarray with the maximum sum among all subarrays in an array of integers.
• Iterate through the array and keep track of the maximum sum subarray seen so far.

• At each index, decide whether to include the current element in the subarray or start a new subarray.

• Update the maximum sum subarray if a new maximum is found.

• Consider edge cases like all negative numbers in the array.

• Example: For input N=5, arr=[
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Round duration - 95 Minutes
Round difficulty - Hard

Round included Data Structures, System Design, Puzzle and HR based questions

Q1. 
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. 
To find the K-th smallest element in a BST, perform an in-order traversal and return the K-th element encountered.
• Perform in-order traversal of the BST to get elements in increasing order

• Keep track of the count of elements visited and return the K-th element

• Time complexity can be optimized by maintaining a count of nodes in each subtree
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Q2. Can you design a system for a website similar to Instagram that caters to travelers?
Ans. 
A website similar to Instagram for travelers, allowing users to share photos and stories from their trips.
• Include features like geotagging to show where photos were taken

• Allow users to create travel itineraries and share tips with others

• Implement a rating system for destinations and accommodations

• Enable users to connect with fellow travelers and plan trips together
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