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DSA Arrays - Practice Questions 2026

Name: DSA Arrays - Practice Questions 2026
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Rating: 4.5 (150 reviews)

Course Description

Mastering Data Structures and Algorithms is the cornerstone of passing technical interviews at top-tier companies. Arrays are the most fundamental yet versatile data structure you will encounter. This comprehensive practice course is designed to take you from a basic understanding to expert-level problem-solving through a series of rigorous, curated practice exams.

Why Serious Learners Choose These Practice Exams

In a competitive job market, simply knowing how to declare an array is not enough. Serious learners choose this course because it bridges the gap between theory and application. Unlike standard tutorials that provide passive learning, these practice exams force you to think critically, analyze time complexity, and recognize patterns.

Each question is crafted to mimic real-world interview scenarios used by FAANG companies. By engaging with our extensive question bank, you build the "muscle memory" needed to identify the most efficient algorithms under pressure. We provide deep dives into every solution, ensuring you understand the "why" behind every "how."

Course Structure

This course is organized into a progressive learning path to ensure no gaps in your knowledge:

Basics / Foundations: This section focuses on the underlying mechanics of arrays. You will be tested on memory allocation, indexing, and the differences between static and dynamic arrays. It is the perfect starting point to ensure your fundamentals are rock solid.

Core Concepts: Here, we move into fundamental operations. You will face questions regarding linear search, basic sorting, and simple array transformations. This section ensures you can handle the "bread and butter" tasks of array manipulation.

Intermediate Concepts: This level introduces multi-pointer techniques, sliding windows, and prefix sums. These are the most common patterns found in mid-level engineering interviews.

Advanced Concepts: Challenge yourself with complex multidimensional array problems, binary search variations on rotated arrays, and sophisticated optimization problems that require a deep understanding of space-time tradeoffs.

Real-world Scenarios: These questions move away from abstract math and into practical application. You will solve problems framed as real software engineering challenges, teaching you how to apply DSA to actual product development.

Mixed Revision / Final Test: The ultimate challenge. This section pulls questions from all previous modules in a timed environment, simulating the pressure of a live technical assessment.

Sample Practice Questions

Question 1

What is the time complexity of accessing an element at a specific index in a dynamic array (like an ArrayList in Java or a vector in C++)?

Option 1: O(n)

Option 2: O(log n)

Option 3: O(1)

Option 4: O(n log n)

Option 5: O(n^2)

Correct Answer: Option 3

Correct Answer Explanation: Arrays are stored in contiguous memory locations. Because the starting address and the size of each element are known, the computer can calculate the exact memory address of any index using a simple formula. This allows for constant time access, or O(1).

Wrong Answers Explanation:

Option 1: O(n) is wrong because this represents a linear search where you must visit every element, which is not required for indexed access.

Option 2: O(log n) is wrong as this is typical for tree-based structures or binary search, not direct index access.

Option 4: O(n log n) is wrong because this usually applies to efficient sorting algorithms.

Option 5: O(n^2) is wrong because this represents quadratic time, typically seen in nested loops, which is far too slow for simple access.

Question 2

When inserting an element at the very beginning of an array of size n, how many elements must be shifted?

Option 1: 0 elements

Option 2: 1 element

Option 3: n/2 elements

Option 4: n elements

Option 5: log n elements

Correct Answer: Option 4

Correct Answer Explanation: In a standard array, to insert an element at index 0, every existing element from index 0 to n-1 must be moved one position to the right to make room. Therefore, all n elements are shifted.

Wrong Answers Explanation:

Option 1: 0 elements is wrong as this only happens if you are appending to the end of an array with available capacity.

Option 2: 1 element is wrong because shifting only one element would overwrite the second element in the array.

Option 3: n/2 elements is wrong because that would only be the case if you were inserting into the exact middle of the array.

Option 4: log n elements is wrong as shifting is a linear operation, not a logarithmic one.

Question 3

Which technique is most efficient for finding a subarray with a specific sum in an array of non-negative integers?

Option 1: Brute force nested loops

Option 2: Sliding Window

Option 3: Binary Search on the whole array

Option 4: Quicksort

Option 5: Depth First Search

Correct Answer: Option 2

Correct Answer Explanation: The Sliding Window technique allows you to maintain a running sum by adding the next element and removing elements from the start of the window as needed. This allows the problem to be solved in O(n) time.

Wrong Answers Explanation:

Option 1: Brute force is wrong because it requires O(n^2) time, making it inefficient for large datasets.

Option 3: Binary Search is wrong because it is used for finding a specific value in a sorted list, not for calculating subarray sums.

Option 4: Quicksort is wrong because sorting the array would destroy the contiguous nature of the subarrays, making the sum irrelevant.

Option 5: Depth First Search is wrong because it is a graph/tree traversal algorithm and is not applicable to simple array sum problems.

Get Started Today

Welcome to the best practice exams to help you prepare for your DSA Arrays. We have built this course to be the only resource you need to master this topic.