Arrays | Must-known DSA Array Techniques

Webinar by Scalar and Naman Bhalla
What are Arrays?
*Linear Data Structure
*A way to store data of the same time
*Allows to get a value at any position in O(1) time

How to implement Arrays in Java ?

in Java:
int[] arrayName =new int[size]

in javascript/python:
we can store different data types because it point to the object referencing
array implementation in python and js

How does Array store data?
Array store data in different address of the RAM
int arr[4]- each int is 4 byte, 4*4 elements
16 byte is allocated when we run the program.

=

Finding Element in Arrays-
if the array is 0 indexed then , if we have to find the 3rd element, then we look for 3-1 i.e. n-1 multiple from the start position/index

13+2*4= 13+8=21 so element will be stored at 21th address

*Dynamic Arrays- *
in case of JS and python
in dynamic array no need to tell the size of the array, you can keep adding the elements infinitely, but it has to be restricted by RAM size or till the time out of memory size

in C++- Vectors
in Java- ArrayList
in Python-
in js - {}(list)

How Dynamic arrays work-
Dynamic array offer capacity and size.
capacity is arbitrary value defined by the programming language, size can be defined by user.

when array gets full initial capacity, the dynamic arrays provides extra capacity of 1.75* or 2*, depending on the programming language, this is all happening behind the scenes.

for N insertion :
the worst case is when added array will lead to creation of the new element and size increase.
time to insert+ capacity time or creating array + copy time
=N+[2N+ 2N/2+ 2N/4+.....]+[N+N/2+N/4+....]
=N+4N+2N=7N

sum of (1+1/2+1/4+1/8.....) will always be less than 2
for N insertion is nN/n = N
time complexity: O(1)

the Dynamic array has no loss, so feel free to use day to day and dynamic programming.
initialization and putting the value:
Vector array[]

array.push(11)

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Kritika Agarwal Software Engineer II at Microsoft