Schrodinger Software Engineer Interview Questions and Answers

Round duration - 65 Minutes
Round difficulty - Medium

This was an online proctured coding test where we had 2 questions to solve under 65 minutes. Both the questions were of difficulty Medium to Hard.

Q1. 
Make Array Elements Equal Problem Statement
Given an integer array, your objective is to change all elements to the same value, minimizing the cost. The cost of changing an element from x to y is defined ...read more
Ans. 
Find the minimum cost to make all elements of an array equal by changing them to a common value.
• Calculate the median of the array and find the sum of absolute differences between each element and the median.

• Sort the array and find the median element, then calculate the sum of absolute differences between each element and the median.

• If the array has an even number of elements, consider the average of the two middle elem
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Q2. 
Pattern Matching Problem Statement
Given a pattern as a string and a set of words, determine if the pattern and the words list align in the same sequence.
Input:
T (number of test cases)
For each test ca...read more
Ans. 
Given a pattern and a list of words, determine if the words align with the pattern.
• Create a mapping between characters in the pattern and words in the list.

• Check if the mapping preserves the order of characters in the pattern.

• Return 'True' if the sequence of words matches the order of characters in the pattern, else return 'False'.
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Round duration - 50 Minutes
Round difficulty - Medium

This round had 2 algorithmic questions in which I first had to explain my approach with proper complexity analysis and then code the solution in any preferred IDE.

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Find pairs of elements in an array that sum up to a given value, sorted in a specific order.
• Iterate through the array and for each element, check if the complement (S - current element) exists in a hash set.

• If the complement exists, add the pair to the result list.

• Sort the result list based on the criteria mentioned in the question.

• Return the sorted list of pairs.
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Q2. 
Merge Overlapping Intervals Problem Statement
Given a specified number of intervals, where each interval is represented by two integers denoting its boundaries, the task is to merge all overlapping interv...read more
Ans. 
Merge overlapping intervals and return sorted list of merged intervals.
• Iterate through intervals and merge overlapping ones

• Sort merged intervals based on starting times

• Handle edge cases like empty input or single interval

• Example: Input - [[1,4], [3,5], [6,8], [10,12], [8,9]], Output - [[1,5], [6,9], [10,12]]
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 1 standard coding question followed by some questions from OS and at last I was also asked some questions related to Statistics and Probability.

Q1. 
Spiral Matrix Problem Statement
You are given a N x M matrix of integers. Your task is to return the spiral path of the matrix elements.
Input
The first line contains an integer 'T' which denotes the nu...read more
Ans. 
The task is to return the spiral path of elements in a given matrix.
• Iterate through the matrix in a spiral path by adjusting the boundaries at each step.

• Keep track of the direction of traversal (right, down, left, up) to cover all elements.

• Handle edge cases such as when the matrix is a single row or column.

• Implement the spiral path traversal algorithm efficiently to meet the time limit.

• Ensure to print the elements in t
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Q2. How can you print numbers from 1 to 100 using more than two threads in an optimized approach?
Ans. 
Use multiple threads to print numbers from 1 to 100 in an optimized approach.
• Divide the range of numbers (1-100) among the threads to avoid overlap.

• Use synchronization mechanisms like mutex or semaphore to ensure orderly printing.

• Consider using a shared variable to keep track of the current number being printed.
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Q3. What is meant by multitasking and multithreading in operating systems?
Ans. 
Multitasking refers to the ability of an operating system to run multiple tasks concurrently, while multithreading involves executing multiple threads within a single process.
• Multitasking allows multiple processes to run simultaneously on a single processor, switching between them quickly.

• Multithreading enables a single process to execute multiple threads concurrently, sharing resources like memory and CPU time.

• Multita...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my role.

Q1. What do you know about the company?
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Q2. Why should we hire you?
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Round duration - 65 Minutes
Round difficulty - Medium

This was an online proctured coding round where we had 2 questions to solve under 1 hour. Both the questions were preety standard and anyone with a decent grip on Data Structures and Algorithms can solve them.

Q1. 
Split Binary String Problem Statement
Chintu has a long binary string str. A binary string is a string that contains only 0 and 1. He considers a string to be 'beautiful' if and only if the number of 0's ...read more
Ans. 
Find the maximum number of beautiful substrings that a binary string can be split into.
• Count the number of 0's and 1's in the string.

• Iterate through the string and split it whenever the count of 0's and 1's becomes equal.

• Return the maximum number of beautiful substrings that can be formed.
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Q2. 
Shortest Path in a Binary Matrix Problem Statement
Given a binary matrix of size N * M where each element is either 0 or 1, find the shortest path from a source cell to a destination cell, consisting only...read more
Ans. 
Find the shortest path in a binary matrix from a source cell to a destination cell consisting only of 1s.
• Use Breadth First Search (BFS) algorithm to find the shortest path.

• Keep track of visited cells to avoid revisiting them.

• Update the path length as you traverse the matrix.

• Return -1 if no valid path exists.
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 coding questions , the first one was related to Sorting and the second one was related to Hashing. After the coding questions, I was asked some concepts related to OOPS in general.

Q1. 
Rahul And Minimum Subarray Problem Statement
Rahul is mastering arrays. He is tasked to find the length of the smallest contiguous subarray in a given array/list ARR of size N, such that its sum exceeds a...read more
Ans. 
Find the length of the smallest subarray in a given array whose sum exceeds a specified value.
• Iterate through the array while keeping track of the sum of the current subarray.

• Use two pointers to maintain a sliding window approach to find the smallest subarray.

• Update the minimum length of the subarray whenever the sum exceeds the specified value.

• Return the length of the smallest subarray found.

• Handle cases where no suba...read more
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Q2. 
Count Subarrays with Sum Divisible by K
Given an array ARR and an integer K, your task is to count all subarrays whose sum is divisible by the given integer K.
Input:
The first line of input contains an...read more
Ans. 
Count subarrays with sum divisible by K in an array.
• Iterate through the array and keep track of prefix sum modulo K.

• Use a hashmap to store the frequency of prefix sum remainders.

• For each prefix sum remainder, count the number of subarrays that sum up to a multiple of K.

• Handle cases where the prefix sum itself is divisible by K.

• Return the total count of subarrays with sum divisible by K.
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Q3. What are virtual destructors in C++?
Ans. 
Virtual destructors in C++ are used to ensure that the correct destructor is called when deleting an object through a base class pointer.
• Virtual destructors are declared with the 'virtual' keyword in the base class to allow proper cleanup of derived class objects.

• When deleting an object through a base class pointer, having a virtual destructor ensures that the destructor of the derived class is called.

• Without a virtual...read more
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Q4. What is the difference between a constructor and a method in Object-Oriented Programming?
Ans. 
Constructor is a special method used to initialize objects, while a method is a function that performs a specific task.
• Constructor is called automatically when an object is created, while a method is called explicitly by the programmer.

• Constructors have the same name as the class, while methods have unique names.

• Constructors do not have a return type, while methods have a return type.

• Constructors are used to set initia...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 coding questions both related to Linked List followed by an interesting puzzle and then a question related to Probability.

Q1. 
Divide Linked List Into Two Problem Statement
You have been given a singly linked list of integers. Your task is to divide this list into two smaller singly linked lists wherein the nodes appear in an alt...read more
Ans. 
Divide a singly linked list into two smaller lists with nodes appearing in an alternating fashion.
• Iterate through the original linked list and assign nodes alternatively to the two smaller lists.

• Handle cases where creating either of the sub-lists is impossible by returning an empty list.

• Ensure to properly terminate the linked lists with -1 at the end of each list.

• Consider the constraints provided while implementing the...read more
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Q2. 
Intersection of Linked List Problem
You are provided with two singly linked lists containing integers, where both lists converge at some node belonging to a third linked list.
Your task is to determine t...read more
Ans. 
Find the node where two linked lists merge.
• Traverse both lists to find their lengths and the difference in lengths

• Move the pointer of the longer list by the difference in lengths

• Move both pointers simultaneously until they meet at the merging point
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my role.

Q1. Why should we hire you?
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Round duration - 65 Minutes
Round difficulty - Medium

This was an online proctured coding test where we had 2 questions to solve under 65 minutes. Both the questions were of difficulty Medium to Hard.

Q1. 
Minimum Travel Cost Problem
You are given a country called 'Ninjaland' with 'N' states, numbered from 1 to 'N'. These states are connected by 'M' bidirectional roads, each with a specified travel cost. Th...read more
Ans. 
Find the minimum cost selection of roads to travel to every state in a country.
• Create a graph representation of the states and roads with their costs.

• Use a minimum spanning tree algorithm like Kruskal's or Prim's to find the optimal roads.

• Select 'N' - 1 roads with the lowest costs to cover all states.

• Return the selected roads and their costs as output.
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Q2. 
Reverse Words in a String: Problem Statement
You are given a string of length N. Your task is to reverse the string word by word. The input may contain multiple spaces between words and may have leading o...read more
Ans. 
Reverse words in a string while handling leading, trailing, and multiple spaces.
• Split the input string by spaces to get individual words

• Reverse the order of the words

• Join the reversed words with a single space in between
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Round duration - 60 Minutes
Round difficulty - Medium

In this round , the interviewer first asked me two algorithmic questions - the first one related to stacks and the second one was of Dynamic Programming. I was able to find the optimal approach for the both the questions and also discussed the time and space complexities. This was followed by some standard questions from OOPS.

Q1. 
Next Greater Element Problem Statement
You are given an array arr of length N. For each element in the array, find the next greater element (NGE) that appears to the right. If there is no such greater ele...read more
Ans. 
The task is to find the next greater element for each element in an array to its right, if no greater element exists, return -1.
• Iterate through the array from right to left and use a stack to keep track of elements.

• Pop elements from the stack until a greater element is found or the stack is empty.

• Store the next greater element for each element in the output array.
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Q2. 
Longest Increasing Path in Matrix Problem Statement
Given a 2-D matrix mat with 'N' rows and 'M' columns, where each element at position (i, j) is mat[i][j], determine the length of the longest increasing...read more
Ans. 
The problem involves finding the length of the longest increasing path in a 2-D matrix starting from a given cell.
• Create a recursive function to explore all possible paths from a cell to its neighboring cells.

• Use memoization to avoid redundant calculations and improve efficiency.

• Keep track of the length of the longest increasing path found so far.

• Consider edge cases such as when the matrix is empty or when there are no...read more
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Q3. What is meant by inheritance in object-oriented programming?
Ans. 
Inheritance in OOP allows a class to inherit properties and behaviors from another class.
• Inheritance allows for code reusability by creating a new class based on an existing class.

• The new class (subclass) can access all the properties and methods of the existing class (superclass).

• Example: A 'Car' class can inherit from a 'Vehicle' class, gaining attributes like 'speed' and methods like 'drive'.
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Q4. What do you mean by virtual functions in C++?
Ans. 
Virtual functions in C++ allow a function to be overridden in a derived class, enabling polymorphic behavior.
• Virtual functions are declared in a base class with the 'virtual' keyword.

• They are intended to be overridden in derived classes to provide specific implementations.

• When a virtual function is called through a base class pointer or reference, the actual function to be called is determined at runtime based on the o...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions from DSA followed by some questions from basics of DBMS and then I was asked some interesting questions from Probability.

Q1. 
Top View of Binary Tree
Given a binary tree of integers, the task is to return the top view of the given binary tree. The top view of the binary tree is the set of nodes visible when viewed from the top.
...read more
Ans. 
Return the top view of a binary tree given in level-order format.
• Use a map to store the horizontal distance of each node from the root

• Perform a level-order traversal and keep track of the horizontal distance of each node

• For each horizontal distance, store the node value if it is the first node encountered at that distance
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Q2. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.
• Implement a doubly linked list to maintain the order of recently used keys.

• Use a hashmap to store key-value pairs for quick access.

• Update the order of keys in the linked list on get and put operations.

• Evict the least recently used key when the cache reaches its capacity.

• Handle edge cases like key not fo...read more
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Q3. What is the main difference between UNION and UNION ALL?
Ans. 
UNION combines and removes duplicates, UNION ALL combines without removing duplicates.
• UNION removes duplicates, UNION ALL does not

• UNION is slower than UNION ALL as it has to check for duplicates

• UNION is used when you want to combine and remove duplicates, UNION ALL is used when you want to combine without removing duplicates
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Q4. What is the probability of obtaining a sum of 22 or more when four dice are thrown?
Ans. 
The probability of obtaining a sum of 22 or more when four dice are thrown.
• Calculate the total number of outcomes when four dice are thrown.

• Determine the number of outcomes where the sum is 22 or more.

• Divide the favorable outcomes by the total outcomes to get the probability.

• Use combinations and permutations to calculate the probabilities.
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round .HR was very frank and asked standard questions. Then we discussed about my
role.

Q1. Why should we hire you?
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Q2. What is something about you that is not included in your resume?
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