Apple Software Development Engineer Test Interview Questions and Answers

Round duration - 120 Minutes
Round difficulty - Medium

The round had 2 coding problems to solve with varying difficulty. Each candidate had a different set of questions. The round was around 2 pm. The webcam was turned on to keep an eye on candidates.

Q1. 
Bursting Balloons Problem
Given an array ARR of size N, where each element represents the height of a balloon. The task is to destroy all balloons by shooting arrows from left to right. When an arrow hits...read more
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Q2. 
Count Leaf Nodes in a Binary Tree
Count the number of leaf nodes present in a given binary tree. A binary tree is a data structure where each node has at most two children, known as the left child and the...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions related to DSA. I was first asked to explain my approach with proper complexity analysis and then code the soution in any IDE that I prefer.

Q1. 
Rod Cutting Problem Statement
Given a rod of a certain length, the rod can be divided into different sizes, each with an associated cost. Your task is to determine the maximum cost that can be obtained by...read more
Ans. 
The Rod Cutting Problem involves maximizing the profit obtained by cutting a rod into smaller pieces and selling them.
• Use dynamic programming to solve this problem efficiently.

• Create a table to store the maximum profit for each sub-length of the rod.

• Iterate through the rod lengths and update the table with the maximum profit.

• The final answer will be the maximum profit for the total length of the rod.
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Q2. 
Count Subarrays with Given XOR Problem Statement
You are given an array of integers ARR and an integer X. Your task is to determine the number of subarrays of ARR whose bitwise XOR is equal to X.
Example...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions of DSA of Easy-Medium difficulty and at the end I was asked a Puzzle to check my general problem solving ability.

Q1. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
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Q2. 
Detect and Remove Loop in Linked List
For a given singly linked list, identify if a loop exists and remove it, adjusting the linked list in place. Return the modified linked list.
Expected Complexity:
A...read more
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Q3. You have two wires of different lengths that are both capable of burning for exactly one hour when ignited at both ends. How can you measure a time interval of 45 minutes using these two wires?
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Round duration - 50 Minutes
Round difficulty - Medium

This round had 2 Algorithmic questions wherein I was supposed to code both the problems after discussing their
approaches and respective time and space complexities . After that , I was grilled on some OOPS concepts related to C++.

Q1. 
Longest Palindromic Substring Problem Statement
You are provided with a string STR of length N. The task is to find the longest palindromic substring within STR. If there are several palindromic substring...read more
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Q2. 
Quick Sort Problem Statement
You are provided with an array of integers. The task is to sort the array in ascending order using the quick sort algorithm.
Quick sort is a divide-and-conquer algorithm. It ...read more
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Q3. What are friend functions in C++?
Ans. 
Friend functions in C++ are functions that are not members of a class but have access to its private and protected members.
• Friend functions are declared inside a class with the keyword 'friend'.

• They can access private and protected members of the class.

• They are not member functions of the class, but have the same access rights as member functions.

• Friend functions are useful for implementing operators that are not part ...read more
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Q4. What is the difference between Early Binding and Late Binding in C++?
Ans. 
Early binding is resolved at compile time while late binding is resolved at runtime in C++.
• Early binding is also known as static binding, where the function call is resolved at compile time based on the type of the object.

• Late binding is also known as dynamic binding, where the function call is resolved at runtime based on the actual type of the object.

• Early binding is faster as the function call is directly linked to ...read more
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Round duration - 60 minutes
Round difficulty - Easy

This was coding round and was conducted on Cocubes platform. It is not IDE but kind of white board coding platform. C/C++, Java and Python were only allowed languages.

Round duration - 30 minutes
Round difficulty - Easy

This was pen and paper round. Total 40 shortlisted candidates were grouped into 8 groups (each of 5). Each group was given a coding question which they have to solve on paper and explain it to the recruiter. 2 to 3 from each group were selected for the next round.

Round duration - 60 minutes
Round difficulty - Easy

This was general face to face Data Structures and Algorithms based round.

Q1. How do you perform a spiral order traversal of a binary tree? Please provide an explanation or code to print the binary tree in spiral order.
Ans. 
Spiral order traversal of a binary tree involves printing nodes level by level alternating between left to right and right to left.
• Start by pushing the root node into a queue.

• While the queue is not empty, pop a node, print its value, and push its children into the queue.

• For each level, alternate between printing nodes from left to right and right to left.

• Repeat until all nodes are printed in spiral order.
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Round duration - 45 minutes
Round difficulty - Easy

It was the last round.

Round duration - 180 minutes
Round difficulty - Easy

This was Online Coding round on Samsung Software. There were 50 test cases and all test cases should be passed to get selected.

Round duration - 30 minutes
Round difficulty - Easy

This was also Face to Face coding Interview totally based on Data Structures and Algorithms.

Q1. The Longest Increasing Subsequence (LIS) problem is to find the length of the longest subsequence of a given sequence such that all elements of the subsequence are sorted in increasing order.
Ans. 
The Longest Increasing Subsequence (LIS) problem is to find the length of the longest subsequence of a given sequence with increasing order.
• Use dynamic programming to solve the LIS problem efficiently.

• Maintain an array to store the length of the LIS ending at each element.

• Iterate through the array and update the LIS length based on previous elements.

• Example: For input [10, 22, 9, 33, 21, 50, 41, 60, 80], the LIS is [10...read more
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Round duration - 30 minutes
Round difficulty - Easy

This Face to Face Interview was Based on coding and projects.

Q1. Implement the Depth First Search (DFS) algorithm for a graph.
Ans. 
DFS is a graph traversal algorithm that explores as far as possible along each branch before backtracking.
• Start at a node and explore as far as possible along each branch before backtracking

• Use a stack to keep track of nodes to visit

• Mark visited nodes to avoid revisiting them

• Recursive implementation is common
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Round duration - 15 minutes
Round difficulty - Easy

HR round was mainly based on questions about myself and my knowledge about the company.

Q1. Tell me about yourself and your family background.
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Round duration - 120 Minutes
Round difficulty - Hard

This round had 3 preety good questions to be solved under 2 hours . The first question was from Graphs and DSU , the second question was related to DP and the third one was from Recursion.

Q1. 
Most Stones Removed with Same Row or Column
On a 2-D plane, there are ‘N’ stones placed at some integer coordinate points. Each coordinate point can have at most one stone. A stone can be removed if it sh...read more
Ans. 
Given a 2-D plane with stones at integer coordinate points, find the maximum number of stones that can be removed by sharing the same row or column.
• Iterate through the stones and create a graph where stones in the same row or column are connected.

• Use depth-first search (DFS) to find connected components in the graph.

• The maximum number of stones that can be removed is the total number of stones minus the number of conne...read more
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Q2. 
Gold Mine Problem Statement
You are provided with a gold mine, represented as a 2-dimensional matrix of size N x M with N rows and M columns. Each cell in this matrix contains a positive integer represent...read more
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Q3. 
All Possible Balanced Parentheses Problem Statement
Given a positive integer N, generate all possible sequences of balanced parentheses using N pairs of parentheses.
A sequence of brackets is called bala...read more
Ans. 
Generate all possible sequences of balanced parentheses using N pairs of parentheses.
• Use backtracking to generate all possible combinations of balanced parentheses.

• Keep track of the number of opening and closing parentheses used.

• Add opening parentheses if there are remaining, and add closing parentheses only if there are more opening parentheses than closing.

• Recursively generate all valid combinations.

• Return the list o...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions from DSA. Both the questions were preety straightforward and were asked to check my implementation skills and how well do I handle Edge Cases for tricky problems.

Q1. 
Stack using Two Queues Problem Statement
Develop a Stack Data Structure to store integer values using two Queues internally.
Your stack implementation should provide these public functions:
Explanation:
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Q2. 
Rotate Matrix by 90 Degrees Problem Statement
Given a square matrix 'MATRIX' of non-negative integers, rotate the matrix by 90 degrees in an anti-clockwise direction using only constant extra space.
Inpu...read more
Ans. 
Rotate a square matrix by 90 degrees in an anti-clockwise direction using constant extra space.
• Iterate through each layer of the matrix and swap elements in groups of 4

• Transpose the matrix and then reverse each row to achieve the rotation

• Ensure to handle edge cases like odd-sized matrices
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Round duration - 60 Minutes
Round difficulty - Medium

This round also had 2 questions related to DSA where I was first expected to explain my approaches and then discuss the time and space complexities of my solution. After that , I was asked some core concepts related to OOPS and OS.

Q1. 
Triplets with Given Sum
Given an array ARR consisting of N integers, find all distinct triplets in the array that add up to a given number K.
Example:
Input:
T = 2
N = 5
ARR = [1, 2, 3, 4, 5]
K = 9
N = 4
...read more
Ans. 
Find all distinct triplets in an array that add up to a given number.
• Use three nested loops to iterate through all possible triplets.

• Sort the array first to easily skip duplicates.

• Use two-pointer technique to find the remaining element for each triplet.

• Handle edge cases like empty list or no triplet summing up to K.
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Q2. 
Trapping Rain Water Problem Statement
You are given a long type array/list ARR of size N, representing an elevation map. The value ARR[i] denotes the elevation of the ith bar. Your task is to determine th...read more
Ans. 
Calculate the total amount of rainwater that can be trapped between given elevations in an array.
• Iterate through the array and calculate the maximum height on the left and right of each bar.

• Calculate the amount of water that can be trapped at each bar by taking the minimum of the maximum heights on the left and right.

• Sum up the trapped water at each bar to get the total trapped water for the entire array.
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Q3. What is the Diamond Problem in C++ and how can it be resolved?
Ans. 
Diamond Problem is a multiple inheritance issue in C++ where a class inherits from two classes that have a common base class.
• Diamond Problem occurs when a class inherits from two classes that have a common base class, leading to ambiguity in accessing members.

• It can be resolved in C++ using virtual inheritance, where the common base class is inherited virtually to avoid duplicate copies of base class members.

• Example: c...read more
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Q4. What is thrashing in operating systems?
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Round duration - 30 Minutes
Round difficulty - Easy

This was my last round and I hoped it to go good just like the other rounds. The interviewer was very straight to point and professional. The interview lasted for 30 minutes.

Q1. What is something about you that is not included in your resume?
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Round duration - 120 Minutes
Round difficulty - Medium

This was an online coding round where we had 3 questions to solve under 120 minutes. The questions were of medium to hard difficulty level.

Q1. 
Minimum Time in Wormhole Network
Determine the minimum time required to travel from a starting point to a destination point in a two-dimensional coordinate system, considering both direct movement and the...read more
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Q2. 
Substrings Differ by One Problem Statement
Ninja needs help in a battle against the string man. Given two strings, 'S' and 'T', the task is to find the number of substrings in 'S' that differ from some su...read more
Ans. 
The task is to find the number of substrings in 'S' that differ from some substrings of 'T' by exactly one character.
• Iterate through all substrings of 'S' and 'T' and compare them character by character to find the ones that differ by exactly one character.

• Use nested loops to generate all possible substrings of 'S' and 'T'.

• Count the number of substrings that differ by exactly one character and return the total count.
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Q3. 
Power of Two Problem Statement
Determine whether a given integer N is a power of two. Return true if it is, otherwise return false.
Explanation
An integer 'N' is considered a power of two if it can be e...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions related to DSA where I was first expected to explain my approaches and then discuss the time and space complexities of my solution. After that , I was asked some core concepts related to OS.

Q1. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
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Q2. 
Cycle Detection in Undirected Graph Problem Statement
You are provided with an undirected graph containing 'N' vertices and 'M' edges. The vertices are numbered from 1 to 'N'. Your objective is to determi...read more
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Q3. What are the differences between a mutex and a semaphore?
Ans. 
Mutex is used for exclusive access to a resource by only one thread at a time, while semaphore can allow multiple threads to access a resource simultaneously.
• Mutex is binary semaphore with ownership, used for mutual exclusion.

• Mutex is typically used to protect critical sections of code.

• Semaphore is a signaling mechanism, used for synchronization between multiple threads.

• Semaphore can have a count greater than 1, allowi...read more
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Q4. 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 to give the illusion of parallel execution.

• Multithreading involves breaking a process into multiple threads that can be executed ind...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 Algorithmic questions wherein I was supposed to code both the problems after discussing their
approaches and respective time and space complexities . After that , I was grilled on some OOPS concepts related to C++.

Q1. 
Trapping Rain Water Problem Statement
You are given a long type array/list ARR of size N, representing an elevation map. The value ARR[i] denotes the elevation of the ith bar. Your task is to determine th...read more
Add your answer
Q2. 
Find The Repeating And Missing Number Problem Statement
You are provided with an array nums which contains the first N positive integers. In this array, one integer appears twice, and one integer is missi...read more
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Q3. What is the Diamond Problem in C++ and how can it be resolved?
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Q4. What are friend functions in C++?
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