https://github.com/katiechurchwell/data-structures

Demystifying Data Structures Notes by Brook Riggio, 2022 CascadiaJS.
https://github.com/katiechurchwell/data-structures

data-structures notes

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Demystifying Data Structures Notes by Brook Riggio, 2022 CascadiaJS.

• Host: GitHub
• URL: https://github.com/katiechurchwell/data-structures
• Owner: katiechurchwell
• Created: 2022-09-05T17:55:18.000Z (about 2 years ago)
• Default Branch: main
• Last Pushed: 2022-09-06T16:23:04.000Z (about 2 years ago)
• Last Synced: 2024-10-12T12:14:36.004Z (about 1 month ago)
• Topics: data-structures, notes
• Language: JavaScript
• Homepage:
• Size: 1.34 MB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md

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README

        
# Demystifying Data Structures Notes by Brook Riggio, 2022 CascadiaJS

## Intro

![abstraction layers](./images/abstraction-layers.jpg)

- Everytime you create an object, you introduce a layer of abstraction.

- You can swap out any layer.

- Hiding details below, usage API looking up

![computational cycle](./images/cycle.jpg)

> Computational thinking - formulating a problem and expressing it's solution. Process.

- modeling a problem : finding the right details to focus on.

- Computing is instructions and data > processed > result

- Abstractions map to specific problems > make it simpler

## Abstract Data Structures

- Array

- [Linked List](https://my.mindnode.com/3qHEkZSjxuNFsVQvrN3Prm6smDzeLKcKA8P8sZF3)

- [Stack](https://my.mindnode.com/9S8sTq6q68R3S9ZsBMqqZynyMpS6HRVGR7jhqjzk)

- [Queue](https://my.mindnode.com/Ggp2kJzx8z96zAnfaSJGNGwH4tpVCpLsu3PZjF8L)

- [Binary Tree](https://my.mindnode.com/ByphRGZUs9yfqksaLzMqDVsmsTeBaJ2W4ioq1p5p)

  - K-Ary Tree

  - Graph

- [Hashmap](https://my.mindnode.com/ZwYyemgphkpraukAr2xHunfbKhR1bxd7XLL1qtzn)

## Data

- RAM

  - addressable memory, like a spreadsheet; columns & rows.

  - use additional memory for pointers. Linked list.

  - each cell is a node.

## Linked List

- Single linked list you know next but not previous (doubly for both).

- Value and next.

- A collection of nodes where each node holds a value and a pointer to the next node.

- Use cases: version history, carousel/slideshow, API pagination, blockchains.

- Traversed the list, traversal.

- Primary operations: add, traverse, size.

Side note: while is preferable over a for loop when length is unknown.

O notation:

- O of 1 = constant time; don't need to know the length

- 0(n) search

## Stack

- Last in, first out. Pushing and popping one value at a time.

- Examples: browser history, backtracking apps, undo/redo.

- A stack is a collection of nodes where each node holds a value accessible in LIFO order.

## Queue

- FIFO

- JavaScript is event driven programming.

- [What the heck is the event loop anyway? | Philip Roberts | JSConf EU](https://www.youtube.com/watch?v=8aGhZQkoFbQ)

- Messaging services:

  - Amazon SQS

  - RabbitMQ

- A queue is a collection of nodes where each node holds a value accessible in FIFO order.

- O(1) enqueue and dequeue

- Cannot traverse, no random access.

- Priority queue - assign priority to nodes.

## Array

- Ammortizes cost with add, memory offsets.

- Proportionally allocate more RAM room.

- JavaScript uses dynamic arrays.

- Buffer overflow attack. punch through at the end of array and inject code.

- Sortable.

- A collection of values indexed from an initial point in memory individually accessible at an offset.

- Sequential access (for-loop), efficient.

- Reserves memory as it grows: 0(2n) space.

  - A linked list would be 0(1) for inserting in the middle

- Merge sort, quick sort and insert sort.

- Binary search algorithm.

## Binary Tree

- Analogies: [reverse polish notation](https://en.wikipedia.org/wiki/Reverse_Polish_notation), dichotomous key, branching river.

- Examples: AI/ML decision tree, huffman coding (.jpeg compression), etc.

- "Binary search tree" and "B trees" are different than a binary tree.

- Traversing: breadth or width first.

- Full, perfect, complete; root, branch, leaf, height.

- Strengths: O(log n) search, elegant recursion, simplicity of interface

## Hash Maps

- Hashing (used bcrypt in past).

- Key values.

- Analogies: dictionary, GPS coordinates, upc codes, license plates, ssn

- Objects in objects.

- A collection of values labeled with infinite key possibilities stored in a finite amount of memory.

- o(1) time

## Further Research

- Gayle Laakmann McDowell videos