Arrays

Question 1

Definition

Answer 1

it’s a contiguous area of memory consisting of equal sized elements indexed by contiguous integers

Question 2

what is special about an array?

Answer 2

it has constant time access and write O(1)

Question 3

how to calculate the position of an element in an array

Answer 3

array_add + element_size * (i - first_element)

first_element can be 0 or 1

Question 4

how are multi-dimensional arrays are laid out in memory?

Answer 4

Row major or column major

Question 5

Times for common operations? Beginning , middle , end to add or remove element

Answer 5

Add    Remove
Beginning     O(N)   O(N)
because we need to shift all the elements
Middle           O(N)   O(N)
because again we need to shift elements
End                O(1)      O(1)

Question 6

Characteristics Of simple array?

Answer 6

it’s a collection of same type elements
Fixed size
Zero indexed
Same Data type

Question 7

why choose a simple array?

Answer 7

because the more constraints u have on your data structure the smaller it will get meaning it will be faster

Question 8

What are arrays in java?

Answer 8

it’s an object consisting of a numbered list of variable each one can be a primitive type or a reference to an object

Question 9

what is a multidimensional array?

Answer 9

it’s an array of arrays

Question 10

what is a dynamic array?

Answer 10

instead of storing the size of the array we just keep track of the pointer pointing to the array and when we need to resize the array we just make it point to another location of memory but we must simulate it like a real array meaning the normal operations like get and set and remove to be of constant time

Question 11

what are the common implementations of dynamic array in c++ , java , python

Answer 11

vector , arraylist , list and python doesn’t have static arrays

Question 12

what r the runtimes of dynamic arrays like get , set , pushback , remove , size

Answer 12

O(1) , O(1) , O(N) , O(N) , O(1)

Question 13

what is a jagged array?

Answer 13

it’s like a multidimensional array but each row has a different number of data and it’s uses like different days of each month in two dimensional array

Question 14

what are the five requirements in any data structure?

Answer 14

access , insert , delete , find , sort

Question 15

do programming languages always use the same sorting algorithm for the array?

Answer 15

No, they look at the size of the array like .NET uses insertion , heap , quick depending on the size of the array

Question 16

what are the general types of sorting arrays?

Answer 16

u can do an in place sorting or copy the entire array to another one

Question 17

can u sort a custom array of objects using the language built in functionality?

Answer 17

No, u must provide an implementation of your own sorting algorithm

Question 18

how to search in an array?

Answer 18

Linear which is O(N) and sometimes when u search for something u move the variable found to the beginning which will make the algorithm a little bit better and most built in searching uses this and there is binary search which is O(LOG N)

Question 19

how to do a linear search?

Answer 19

u go over every item in the array checking for the value

Question 20

how to do binary search?

Answer 20

u can’t do a binary search on an unordered data set …. u go to the middle of the array if the number is larger u move to the right half and discard the left until u find an element or u don’t