sum1t-here / DSA-grind

Data Structure

- Linear DS (Array, Stack, Queue and many more)
- Non-Linear Ds (Trees, Graphs)

Array

- Contiguous memory location
- default index 0
- random access using arr[index]

Array in python:

Dynamic Array

Methods for array in python

append() : Adds an element at the end of the list

clear() : Removes all elements from the list

copy() : Returns a copy of the list

count() : Returns the number of elements with the specified value

extend() : Add the elements of a list (or any iterable), to the end of the current list

index() : Returns the index of the first element with the specified value

insert() : Adds an element at the specified position

pop() : Removes the element at the specified position

remove() : Removes the first item with the specified value

reverse(): Reverses the order of the list

sort() : Sorts the list

Address of an element in 1D arrray:

arr[i] = Base address + (i - lower Bound of an index) * size of an element

lower bound -> by default 0

2D arrays

 _            _
| 2     4    6 |
| 8     10   12|
| 14    17   20|
|_            _|

Storing 2D in 1D array

- Row major form -> Row wise
- Column major form -> Column wise

Address of element in 2D Row major form

loc (arr[i][j]) = Base address + [(i - Lower bound row) * number of columns + (j - lower bound column)]*size of each element

Address of element in 2D Column major form

loc (arr[i][j]) = Base address +[(j - lower bound column) * number of rows + (i - Lower bound row)]*size of each element

Sorting algorithm

Broadly classified into two types:

• comparision based

  • Selection Sort
  • Bubble Sort
  • Quick Sort
  • Merge Sort
  • Heap Sort

• non-comparision based

  • Count Sort
  • Radix Sort
  • Bucket Sort

Stable and unstable sorting algorithm

Stable: Relative order should be maintained after sorting algorithms

Unstable:

• Quick sort
• Heap sort
• Selection sort

Inplace and outplace sorting algorithm

Inplace: Not using extra space to sort Outplace: Using extra space (Merge sort)