Array Questions at Infosys: What to Expect

Array questions dominate Infosys technical assessments. With 97 out of 158 total questions, arrays are not just a topic—they are the core of the coding interview. A strong performance here directly impacts your hiring outcome. Mastering arrays demonstrates your grasp of fundamental data structures, efficient problem-solving, and ability to handle large-scale data operations, which are critical for Infosys's global IT and consulting projects.

What to Expect — Types of Problems

Infosys array problems typically focus on practical application over complex theory. Expect these categories:

1. Basic Traversal and Operations: Searching, inserting, deleting, or finding sum/min/max. These test your syntax and loop control.
2. Subarray Problems: Finding contiguous subarrays that meet a condition, like maximum sum or a given target sum. These are common.
3. Sorting and Rearrangement: Problems requiring you to sort, rotate, or rearrange elements based on specific rules (e.g., moving zeros to the end).
4. Two-Pointer Techniques: Used for problems involving pairs, reversing parts of an array, or removing duplicates from a sorted array.
5. Frequency Counting: Using hash maps (or objects/dictionaries) to count element occurrences to find duplicates, unique elements, or majority elements.

The difficulty often lies in optimizing for time and space complexity within given constraints.

How to Prepare — Study Tips with One Code Example

Focus on pattern recognition, not memorization. Understand the underlying technique for each problem type. Practice writing clean, compilable code by hand or in a simple editor to simulate the test environment. Always analyze time and space complexity.

A key pattern is the Two-Pointer Technique, often used for problems like reversing an array or finding a pair with a target sum. Here is an example of reversing an array in-place:

def reverse_array(arr):
    left, right = 0, len(arr) - 1
    while left < right:
        # Swap elements
        arr[left], arr[right] = arr[right], arr[left]
        left += 1
        right -= 1
    return arr

Recommended Practice Order

Build your skills progressively. Start with basic traversal and operations to build confidence. Move to sorting and rearrangement problems, which introduce more logic. Then tackle fundamental patterns like the two-pointer technique and frequency counting using hash maps. Finally, concentrate on subarray problems, as these often combine multiple concepts and are a frequent assessment point. Throughout, consistently practice writing bug-free code and stating your complexity analysis.

Practice Array at Infosys