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Array

Introduction Array

Array is the collection of similar datatype or simlar element of object in data structure

An array is defined as a fixed-size collection of elements of the same data type stored in contiguous memory locations. It is the simplest data structure where each element of the array can be accessed by using its index.

Properties of arrays

Each element of the array is of the same data type and same size. For example: For an array of integers with the int data type, each element of the array will occupy 4 bytes.

Elements of the array are stored in contiguous memory locations. For example : 200 is the starting address (base address) assigned to the first element of the array and each element of the array is of integer data type occupying 4 bytes in memory.

Array

Where can arrays be used ?

• Arrays should be used where the number of elements to be stored is already known.
• Arrays are commonly used in computer programs to organize data so that a related set of values can be easily sorted or searched.
• Arrays work well when we have to organize data in multidimensional format. We can declare arrays of as many dimensions as we want.
• If the index of the element to be modified is known beforehand, it can be efficiently modified using arrays due to quick access time and mutability.

Array Advantage

• Code Optimization: It makes the code optimized, we can retrieve or sort the data efficiently.
• Random access: We can get any data located at an index position.

Disadvantages of arrays

• Since arrays are fixed-size data structures you cannot dynamically alter their sizes. It creates a problem when the number of elements the array is going to store is not known beforehand.
• If more memory is allocated than required, it leads to the wastage of memory space and less allocation of memory also leads to a problem.
• Insertion and Deletion in arrays are difficult and costly since the elements are stored in contiguous memory locations, hence, we need to shift the elements to create/delete space for elements.

Types of Array

• 1. Single Dimensional Array
• 2.Multidimensional Array

1 Single Dimensional Array.

Syntax to Declare an Array in Java

dataType[] arr; (or) dataType []arr; (or) dataType arr[];

Instantiation of an Array in Java

arrayRefVar=new datatype[size];

Array Question

• 1. Java Program to copy all elements of one array into another array
• 2. Java Program to find the frequency of each element in the array
• 3. Java Program to print the elements of an array in reverse order
• 4. Java Program to print the elements of an array present on even position and odd position
• 5. Java Program to print the largest element in an array
• 6. Java Program to print the smallest element in an array
• 7. Java Program to print the sum of all the items of the array
• 8. Java Program to sort the elements of an array in ascending order and descending order
• 9. Java Program to Find 2nd Largest Number in an array
• 10. Java Program to Remove Duplicate Element in an array
• 11. How to Sort an Array in Java
• 12. Java Program to right rotate the elements of an array
• 13. Find the "Kth" max and min element of an array
• 14. Find the Union and Intersection of the two sorted arrays.
• 15. Write a program to cyclically rotate an array by one.
• 16. Merge 2 sorted arrays without using Extra space.
• 17. Best time to buy and Sell stock
• 18. Median of 2 sorted arrays of equal size
• 19. Find the triplet that sum to a given value
• 20. Maximum profit by buying and selling a share atmost twice
• 21. Find if there is any subarray with sum equal to 0
• 22. Count Inversion

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