List of 50+ Array Coding Interview Problems
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In this article, we have listed important Problems on Array which you must practice for Coding Interviews and listed introductory and background topics on Array as well. You must bookmark this page and practice all problems listed.
Table of Contents:
 Basics of Array (+ Implementation)
 Types of Array
 Coding Problems on Array
(Important)
Basics of Array (+ Implementation)
Array is a simple Data Structure. Go through the basics of Array and how to implement it in C and C++ Programming Language. This is same for other programming Languages as well. We will attempt Practice Problems following this.
 Array
 Get length of array in C and C++
 Initialize array in C
 Delete an array in C
 2D array in C
(Important)
 3D array in C
Types of Array
Many do not realize that there are different types of Array. Each type is useful for different problems. Some array techniques like Prefix Sum Array will help you solve key Algorithmic Problems.
Go through the different types of Array:
 Dynamic Array
(Important)
 Hashed Array Tree: Efficient representation of Array
(Important)
 Suffix Array
 Prefix Sum Array
(Important)
 Bit Array
(Important)
 Bit Mask/ Map
 Array vs Linked List
Coding Problems on Array
Array is a simple Data Structure but Algorithmic Problems based on array can be challenging to solve efficiently if you are not in practice.
Practice these Coding Problems based on Array:
 Least frequent element in an array
 Largest element in array
 Smallest element in array
 Kth largest element in array stream
Array Rotation (3 techniques) (Important)
 Block swap algorithm for array rotation
 Reversal algorithm for array rotation
 Juggling algorithm for array rotation
Partition an Array (2 techniques) (Important)

Techniques to find Majority element
 General techniques
 Boyer Moore majority vote algorithm: A very important algorithm for Competitive Programming.
More Practice Problems on Array:
 Shuffle an array
(Important)
 Finding 2 elements with difference k in a sorted array
(Important)
 Finding LCM of an array of numbers
 Find GCD of all elements in an array
 Find index such that sum of left subarray = right subarray (Equilibrium Index)
(Important)
 Multiple array range increments in linear time O(N)
 String Matching using Bitset
(Important)
 Pass array in function in C in two ways
 Implementing two stacks in one array
(Important)
 Implementing K stacks in one array
 Move negative elements to front of array
 Stack using array
 Queue using array
 Converting a Sorted Array to Binary Tree
 Minimum Increment and Decrement operations to make array elements equal
 Minimum number of increment (by 1) operations to make elements of an array unique
 Kadane's Algorithm for largest subarray sum
 Minimum number of operations to make GCD of an array K
(Important)
 Minimum number of increment or decrement (by 1) operations to make array in increasing order
 Minimum number of increment (by 1) operations to make array in increasing order
 Smallest Missing Positive Integer
 Set Matrix elements to Zeros
 Make N numbers equal by incrementing N1 numbers
 Rolling Hash
(Important)
 Maximize the sum of array_i * i
 Find Minimum sum of product of two arrays
 The smallest subset with sum greater than sum of all other elements
 Find the Largest lexicographic array with at most K consecutive swaps
 String Matching using Bitset
 Minimum Product Subset of an array
(Important)
 Maximum Product Subset of an array
 Multiple array range increments in linear time O(N)
 Minimum operations to make GCD of array a multiple of k
 Maximize sum of consecutive differences in a circular array
With this article at OpenGenus, you must a strong idea and practice of Array based Problems. Best of Luck with your Interviews and Research.