Hi, I'm Eli 👋

@elibelly

Software Engineer at Twitter

(she/her)

Get your Computer Science degree

in 10 minutes*

@elibelly

*Here are some CS concepts that you might want to know exist or maybe clarify 

@elibelly

What is computer science?

@elibelly

The study of problem solving

@elibelly

1. The scientific and practical approach to computation and its applications.
2. The systematic study of the feasibility, structure, expression, and mechanization of the methodical procedures (or algorithms) that underlie the acquisition, representation, processing, storage, communication of, and access to information.

More formally...

@elibelly

we want to, like, get information or do stuff to it soo how do we science that and then make computers do all the work real fast

Which basically means...

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Algorithms

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What is an algorithm ? 

An unambiguous set of steps to complete a task or computation

It is very much like a recipe for a computer

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Algorithm: Find the max 

Problem: Given a list of positive numbers, we need to return the largest number on the list.

Input: A list, "L", of positive numbers. This list must contain at least one number. 

Output: A number, "n", which will be the largest number of the list.

1. Set "max" to 0.
2. For each number x in the list L, compare it to max. If x is larger, set max to x.
3. "max" is now set to the largest number in the list.

@elibelly

Algorithms & Computer Science 

1. Does an algorithm actually exist to do a thing?
2. Are we totally sure that the algorithm works for all possible inputs?
3. How long does the algorithm take to run?
4. How much memory space does it require?
5. Once we know it’s possible to solve a problem with an algorithm, is the algorithm the best possible one. Can the problem be solved more quickly?

Answering some Qs

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Time Complexity

The amount of time an algorithm takes to run in relation to the number of inputs

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Big O Notation

A mathematical notation that describes a  measure of the execution of a function as the inputs approach infinity 

O( ? )

Example: O( 1 ) , O( n ), O( log n ) where n represents the number of inputs 

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Let's say you want to watch a TV series...

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Let's say you want to watch a box set....

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Let's say you want to watch a box set....

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Let's say you want to watch a box set....

Conclusion: Ordering Online is a more scalable algorithm!

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What is the time complexity of searching for a maximum number in an array? 

[ 34, 7, 0, 4, 12, 11, 104, 3, 19 ]

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Data Structures

A data structure is a particular way of organizing data in a computer so that it can be used efficiently

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Stack

Queue

LIFO

Last In, First Out ordering

FIFO

First In, First Out ordering

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Trees

Graphs

Node-based data structures. A tree is a type of graph.

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Analyzing Time Complexity of Algorithmic Operations on Data Structures

(adding it all together)

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Doing things to information

• Search
• Sort
• Insert
• Find
• Delete

@elibelly

Algorithm: Find the max 

Problem: Given a list of positive numbers, we need to return the largest number on the list.

Input: A list, "L", of positive numbers. This list must contain at least one number. 

Output: A number, "n", which will be the largest number of the list.

1. Set "max" to 0.
2. For each number x in the list L, compare it to max. If x is larger, set max to x.
3. "max" is now set to the largest number in the list.

@elibelly

Unsorted Array

Binary Search Tree

[ 3, 5, 20, 11, 8 ]

[ 8, 3, 11, 5, 20 ]

3

20

11

8

5

@elibelly

Other Topics in Computer Science

• Programming Language Theory 

• Artificial Intelligence

• Databases

• Networking

• Graphics

• Cybersecurity

• Human-Computer Interaction

• Operating Systems

• Compiler Theory 

• Distributed Systems

• Boolean Logic

• Number Theory

• Game Theory

• Bioinformatics

• Big Data

@elibelly

👋

THANKS!

@elibelly