Data Structures & Algorithms #1 - What Are Data Structures?

Summary

In this informative video, YK, a former Google software developer, introduces viewers to the fundamental concepts of data structures and algorithms. Through relatable examples like a neighborhood map and a party scenario, YK illustrates how different data structures, such as arrays and linked lists, can be used to store and retrieve information efficiently. The video emphasizes the importance of these concepts in writing effective software, showcasing their practical applications and encouraging viewers to apply their learning through problem-solving.

Takeaways

• 👋 Introduction: YK, a former Google software developer, now runs a YouTube channel focusing on data structures and algorithms.
• 📚 Definition: Data structures are different ways of storing data on a computer, essential for organizing information efficiently.
• 🗺️ Example Scenario: A neighborhood mapping system using coordinates and street connections to illustrate the need for data structuring.
• 🔍 Data Representation: Two methods discussed for representing data - a list of paths and a table of connections between places.
• 🔑 Data Structures Identified: The list corresponds to an array or list structure, while the table is akin to a hash table or hash map.
• 🤖 Algorithms Defined: A set of operations performed on data structures, providing step-by-step instructions to solve problems.
• 🛣️ Shortest Path Problem: An example of using algorithms to find the shortest path in a neighborhood, highlighting the systematic approach required.
• 🛠️ Efficiency Importance: Emphasizing the importance of data structures and algorithms in writing efficient software, with a personal anecdote from YK's experience at Microsoft.
• 🎉 Party Scenario: A light-hearted example using a party with named balls to compare array and linked list data structures in real-life situations.
• ➡️ Resizing Data Structures: Discussing the ease of resizing linked lists versus arrays, and when each might be preferable based on expected data size.
• 📝 Learning Application: Stressing the importance of applying learned concepts through problem-solving for better understanding and practical use.
• 🌟 Resource Recommendation: YK recommends 'brilliant.org' for an interactive learning experience in computer science fundamentals, including algorithms.

Q & A

What is the one-sentence description of data structures according to the video?

Data structures are different ways of storing data on your computer.

What is an example of a data structure used to represent a neighborhood map with streets and locations?

One example is using a list to store all possible paths between locations, or using a hash table to map each location to all the places one can go from that location.

What is the difference between an array and a hash table as described in the video?

An array or list stores items sequentially, while a hash table or hash map uses key-value pairs to store data, allowing for faster access to elements based on keys.

What is an algorithm according to the video?

An algorithm is a set of operations performed on data structures and a set of instructions for executing them.

Can you explain the example of finding the shortest path from home to school in the video?

The example involves finding all possible paths from home to school, calculating the distance for each path using coordinates, and then selecting the path with the shortest distance.

How does the choice of data structure affect the implementation of an algorithm?

The choice of data structure can make certain operations more efficient or straightforward. For instance, finding all possible places from home is easier with a hash table than with a list.

What is the real-life example given in the video to illustrate data structures?

The real-life example is a party where guests bring balls with their names written on them, which can be stored in an array-like box with partitions or a linked list of individual boxes.

Why is it easier to fix a misspelled name in an array compared to a linked list?

In an array, you can directly access the 98th element by calculating its position, whereas in a linked list, you would need to traverse the list from the beginning to find the 98th element.

How does the video illustrate the advantage of a linked list over an array when more guests arrive unexpectedly?

With a linked list, you can easily add more boxes to the end without affecting the existing structure, whereas with an array, you might need to create a new array with more partitions or transfer elements to a new array.

What is the importance of learning data structures and algorithms as emphasized in the video?

Learning data structures and algorithms helps in writing efficient software, as demonstrated by the example of code optimization that reduced data retrieval time from hours to minutes.

How does the video suggest practicing and applying knowledge of data structures and algorithms?

The video recommends using platforms like Brilliant.org to solve problems related to data structures and algorithms, which helps in understanding and applying the concepts in real-world situations.

Outlines

00:00

📚 Introduction to Data Structures and Algorithms

YK, a former Google software developer, introduces the concept of data structures as different ways to store data on a computer. He uses the analogy of a neighborhood map system to illustrate the need for data structures to understand how locations are connected. The example includes storing coordinates and street connections, comparing list-based and table-based methods. The paragraph also explains algorithms as operations and instructions for data structures, using the shortest path problem as an example to demonstrate the need for systematic problem-solving in computer science.

05:02

🛣️ Data Structures in Real-World Scenarios

The script continues with a detailed explanation of how data structures can be applied to real-world problems, such as finding the shortest path in a neighborhood using algorithms. YK discusses the impact of the choice of data structure on the implementation of an algorithm, using the examples of an array and a hash table. He also shares a personal experience from his time at Microsoft, where knowledge of data structures and algorithms significantly improved the efficiency of his code.

10:03

🎉 Practical Examples of Data Structures

YK presents a hypothetical party scenario to further elucidate data structures. He contrasts the use of an array, represented by a long box with partitions, with a linked list, symbolized by individual boxes connected by strings. The example highlights the advantages and disadvantages of each structure, such as ease of access in an array versus ease of resizing in a linked list. The narrative emphasizes the importance of choosing the right data structure based on the specific requirements of a situation.

15:03

🚀 Embracing Data Structures and Problem Solving

The final paragraph emphasizes the importance of applying learned concepts through problem-solving. YK recommends Brilliant.org for interactive learning of computer science fundamentals, including algorithms, and mentions a special offer for the first 200 visitors from his channel. He concludes by expressing excitement about his first sponsor and invites viewers to join him in the next video for further exploration of data structures.

Keywords

💡Data Structures

Data structures are the different ways of organizing and storing data in a computer so that it can be used efficiently. In the context of the video, they are essential for developing efficient software and algorithms. The script uses examples like a neighborhood map system and a party scenario to illustrate different data structures such as arrays and linked lists.

💡Algorithms

Algorithms are a set of instructions or rules to be followed in order to solve a problem or perform a computation. The video defines them as operations performed on data structures and emphasizes their importance in creating efficient software solutions, such as finding the shortest path in a neighborhood map example.

💡Software Developer

A software developer is a person who designs, codes, and maintains applications or systems software. The video's presenter, YK, identifies as a former software developer at Google, highlighting the relevance of data structures and algorithms in the field.

💡Google Maps

Google Maps is a web service that provides detailed information about geographical locations and routes. The script uses it as an analogy for creating a neighborhood map system, emphasizing the need for efficient data storage and retrieval of location and connectivity information.

💡Latitude and Longitude

Latitude and longitude are geographical coordinates that specify the north-south and east-west position of a point on the Earth's surface, respectively. In the video, they are used to pinpoint the exact location of places in the neighborhood map system example.

💡One-Way Streets

One-way streets are roads that allow traffic to move in only one direction. The script uses one-way streets in the neighborhood map analogy to demonstrate the need for data structures that can represent directional connectivity between locations.

💡Arrays

An array is a data structure consisting of a collection of elements, each identified by one or more indices. The video script uses the concept of an array to illustrate how a list of paths can be stored in a neighborhood map system.

💡Hash Tables

A hash table, also known as a hash map, is a data structure that implements an associative array, a structure that can map keys to values. The script contrasts hash tables with arrays to show different methods of storing connectivity information in the neighborhood map system.

💡Shortest Path

The shortest path problem involves finding the quickest or most direct route between two points. The video uses the example of finding the shortest path from home to school to explain how algorithms can be applied to solve practical problems using data structures.

💡Efficient Software

Efficient software refers to programs that perform well in terms of speed and resource usage. The video emphasizes the importance of understanding data structures and algorithms to write efficient software, as illustrated by YK's experience at Microsoft.

💡Brilliant.org

Brilliant.org is an educational platform that offers courses in various subjects, including computer science. The video mentions it as a resource for learning data structures and algorithms through problem-solving, with a special offer for viewers to support the channel.

Highlights

Introduction to the concept of data structures as different ways of storing data on a computer.

Use of a neighborhood map analogy to explain the need for data structures to represent connections and relationships.

Example of storing paths in a list format to represent one-way streets and their limitations.

Introduction of a table format to represent places and connections, illustrating the hash table or hash map data structure.

Definition of algorithms as operations performed on data structures and sets of instructions for executing them.

Illustration of finding the shortest path in a neighborhood using latitudes and longitudes as an example of an algorithmic problem.

Explanation of how data structures can affect the implementation and efficiency of algorithms.

Personal anecdote from the presenter's experience at Microsoft, highlighting the impact of data structures and algorithms on code performance.

Introduction of a party scenario to further explain the practical applications of data structures like arrays and linked lists.

Comparison of the advantages and disadvantages of using arrays versus linked lists in different situations.

Discussion on the importance of choosing the right data structure based on the specific requirements of a problem.

Emphasis on the practical importance of data structures and algorithms in writing efficient software.

Introduction to the concept of applying learned concepts through problem-solving to solidify understanding.

Promotion of Brilliant.org as a resource for learning computer science concepts through problem-solving.

Mention of a special offer for the first 200 people visiting Brilliant.org through a provided link, including a discount on the annual subscription.

Closing remarks by the presenter, expressing excitement about the first sponsor and looking forward to the next video.

Transcripts

hey YouTube just in case you're new here

my name is YK and I was formerly a

software developer at Google and now I

work on this YouTube channel full time

and welcome to my data structures and

algorithms series number one what are

data structures so a one sentence

description of what data structures are

would be that there are basically

different ways of storing data on your

computer and this sentence might not be

too clear right now so let me give you a

more concrete example here let's say you

want to make a system that's sort of

like Google Maps for your neighborhood

now let's say your neighborhood looks

like this so your home is here and

there's a store here and another store

here and so on and there are some

streets too so these arrows show that

these are one-way streets there are a

lot of one-way streets here and so for

example you can go from store to store B

but not the other way around and all the

other lines here there are not arrows

show that they are two-way streets and

let's say that you already have each

place is coordinates there are latitudes

and longitudes stored on your computer

like this as you can see from this table

you can tell that the latitude of home

is forty-nine point two and the

longitude of home is minus one hundred

twenty three point four and so on now

from this table like information you can

tell where each location is exactly

where each point is exactly but you

can't tell how these locations are

connected with streets and where the

streets are exactly so you need to

figure a way to store that information

somehow on your computer and there are

actually a few different options for

this one of those options will be to

store all possible paths in a list like

format so for example one of those paths

will be from store a to home and another

one will be home to store a and yet

another path will be store a to store B

and with that method your data might

look like this and from this list like

information you can tell that as we saw

earlier you can go from home to store a

and from store a to home and home

to store B and so on but you can't go

from store B to home because this is a

one-way street and so there's no path

from store B to home in this list okay

so that's just one option another option

might be to list each of these places

and for each of those places just list

all the places you can go from that

place and with that method your data

might look like this instead as you can

see here we have table like information

again where on the left hand side we

have all the places listed home store a

store B school and then intersection

this one right here and on the right

hand side for each of those places we

have all the places you can go from

there so from home you can go to store a

store B and intersection as you can see

here and from store a you can go to home

or store B so these two methods are

basically two different ways of storing

exactly the same set of data and as you

can see they have sort of different

structures and so these are simplified

examples of what data structures look

like now if you're already familiar with

data structures you might notice that

the first method corresponds to the

array or a list data structure and the

second method corresponds to the hash

table or hash map data structure okay so

that's one simple example of what data

structures are but this video series is

called data structures and algorithms so

what are algorithms one way to define

what they are would be that there are

the operations we can perform on

different data structures and the sets

of instructions for executing them so

one example here might be something like

this coming back to the previous example

we had let's say you want to find the

shortest path from home to school so in

this problem by hand is pretty easy

pretty much right away you can see that

there are three potential paths from

home to school one of them is this one

just go to store a store B and then

school another one is this one store B

and this

cool and another one the other one is

from home to intersection to school and

for these three paths just compare the

distance that you need to travel for

each of these paths and then pick the

shortest one and to compute the distance

that you need to travel for each of

these paths you can for example use the

longitudes and latitudes the coordinates

of each of these places and find the

distance in kilometers so solving this

problem by hand is pretty much trivial

but if you want to turn this into

something a computer can understand you

need to be much more systematic about it

so to make this strategy something a

computer can understand easily you might

come up with a set of instructions like

this one first of all find all the

places you can go from home so in this

example that's store a store B and then

the intersection and then from each of

those places find all the paths you can

take from that place so from store a you

can go to store B and from store B you

can go to school and from intersection

you can only go to school and as you go

keep track of the distance you've

traveled so far for each of those paths

and keep repeating this process until

you get to the school then if you happen

to find multiple paths that allows you

to go from home to school then compare

the distance that you've traveled for

each of those paths and finally find a

path with the shortest distance traveled

and then pick that as the shortest path

okay so that's the result we were

looking for in the first place and this

is a good example of what an algorithm

is basically you have a problem you're

going to solve in this case finding the

shortest path from home to school and

then you have a set of systematic

instructions for solving that problem

now one thing to note here is that

depending on what data structure you're

using to store the data that you're

performing the algorithm on your

algorithm might look slightly

differently you might even have in some

cases completely different algorithms

for solving the same problem depending

on what data structure you're using

in this particular example we talked

about two different options for storing

the information about where the streets

are and how they connect different

locations the first option was to just

list all possible paths and remember

that the first step in our algorithm was

to find all the possible places you can

go from home and to do that with the

first stair structure this one right

here you might actually need to go

through the entire list because in this

particular list we have three paths here

from home but it's possible that we have

another path from home right here at the

end of the list so you need to go

through the entire list just in case on

the other hand if you use the second

data structure that we discussed we have

all the possible places you can go from

home listed right here as a group so as

soon as we find the home row in this

table you won't need to go through the

entire table anymore so in this

particular example using the second

structure actually makes it slightly

easier to implement the algorithm that

we discussed now there are structures

and algorithms are really important to

learn because they'll help you write

efficient software as a software

developer so for example when I was

working at Microsoft as a data science

intern I had to write this piece of code

to retrieve some data and when I wrote

it originally it was taking like seven

to ten hours and basically it was too

slow because we didn't want we didn't

want to wait that long so I rewrote it

using my knowledge of data structures

and algorithms and after rewriting it

the new version only took like five to

ten minutes to load that data so that's

why learning them is important and it's

actually useful in many practical

situations that you might encounter as a

software developer - okay to give you an

even better idea about what data

structures are like let me give you

another example here let's say you're

hosting a party and you're expecting a

bunch of people and this example is

gonna be a little bit silly but just

follow along and you're gonna see why

I'm talking about this particular

example anyway let's say that each

person

come to the party we'll bring sort of

like a small ball with them like a ball

that can fit in their hand and this ball

will have their name written on it so

when David comes to the party he'll have

a ball with David written on it and when

Kevin arrives to the party he'll have a

ball with Kevin written on it and so on

and this is just a silly little system

that you came up with for keeping track

of who came to the party in which order

because writing now each person's name

would be a lot of work you're just too

busy hosting a party so as someone who's

studying computer science let's say

you're trying to come up with an

efficient system for storing these balls

so that you can keep track of who came

to the party one idea you have is this

one you get a very long box with 100

partitions a lot of partitions and each

partition let's say has exactly the same

shape you know 10 centimeters by 10

centimeters let's say and every time

someone comes to the party you're just

gonna put that person's ball with their

name written on it in the order they

came to the party so David's ball will

come in here and Kevin's will come in

here and so on and this is actually sort

of like a data structure that's realized

in real life and this actually

corresponds to the data structure called

array in computer science and here's

another idea you have you get a bunch of

boxes and this time instead of getting a

long box with many many partitions you

want to get individual boxes that are

connected with strings so the first box

is connected to the second box with a

string and that's connected to the third

box with a string and so on and just

like before you want to put these tokens

with participants names written on them

in these boxes just one by one in the

order they came in so David's token will

come in here and Kevin's ball will come

in here and so on and this sort of data

structure that's realized in real life

corresponds to the linked list data

structure in computer science okay so

the natural question here would be which

data structure

use for this party well it actually

depends because it highly depends on the

particular situation and the nature of

the party really and each data structure

has advantages and disadvantages okay

think about this situation let's say 100

people showed up to your party and

you're pretty happy about it but

suddenly you realize that the 98th

person is Paul had been misspelled that

person's name had been misspelled so you

want to fix that with the array data

structure it's actually pretty easy you

just need to find the 98th partition and

that exact location can be calculated

easily because you know that each

partition is ten centimeters wide so you

just need to find ten centimeters times

ninety seven actually which is nine

hundred seventy centimeters so you just

need to walk over from the beginning

nine hundred seventy centimeters and

then you can find the 98th person's

token pretty easily you just need to

replace that with the correct token with

the link list data structure though

doing the same thing would be slightly

more tricky and that's because finding

the 98th person or finding the 98th box

here would be much harder and the reason

for that is because these strings are

pretty soft and they can be pretty much

any lengths so each box can be in any

location relative to the previous box so

this first box might be in the living

room and the second box might be in the

kitchen and so on so to find in 98th box

what you need to do is you need to count

them one by one so you need to say okay

this is the first box and then this is

the second box and let's find the third

box fourth and so on until you get to

the 98th person at this point you might

say well the array data structure is a

better one then well not necessarily so

think about this situation let's say you

have 100 people showing up to the party

and you're pretty happy about it but

suddenly five more people show up that

you didn't expect with the linked list

data structure it's pretty easy to deal

with that you can just

add five more boxes find five more boxes

somewhere and then five more strings and

just add them to the last box you had in

the linked list data structure and then

store the five people's tokens in those

boxes with the array data structure

though it's a little bit more tricky one

option here would be to get another box

with let's say 100 partitions again and

store those people's tokens there and

use the two boxes together or you could

destroy the first box you had and then

get a box with even more partitions

let's say 200 partitions and then

transfer all the balls you had for the

first 100 people to the new box and then

after that add the additional five

people's tokens in the new box and in

general if you have no idea how many

people are coming to the party let's say

anywhere between 5 to 1,000 people

the linked list data structure might be

slightly more convenient than the array

because linked lists are so much easier

to resize than it is to resize a race ok

and this was another simplified example

of what data structures are like on a

computer and this sort of gives you a

rough idea about how to actually start

thinking about them and throughout this

course I'm going to introduce you to

even more data structures and this time

I'm going to explain them in a much more

technical way using concepts like

classes objects memory and maybe even

some code snippets too now if you're

just getting started with data

structures and algorithms one thing to

keep in mind that's actually really

important is to apply what you've

learned through solving problems and the

reason I say that is because it's so

common for beginners to learn these

concepts and not actually be able to use

them in a real-world situation because

they haven't had enough practice and

actually this video sponsor brilliant

org has an interesting website for

learning these concepts in a sort of a

new way ok to show you what I mean let's

take a look at their computer science

fundamentals course right

here which I would recommend for you

guys and let's go into the intro to

algorithms section and you can see that

it covers topics like arrays searching

insertion sort and Big O notation and in

the arrays section they have a bunch of

explanations about the topic and as you

continue you'll give you a quiz to test

your understanding of the topic so it's

definitely an interesting way to learn

computer science concepts by solving

problems okay if you want to check it

out for yourself just go to brilliant

org slash CS no joke

and going to this link will actually

help support this channel and the first

200 people will get 20% off the annual

subscription and actually I'm super

excited about this because they're the

first sponsor I have on this YouTube

channel and I feel like I'm becoming a

professional youtuber finally so thanks

for that brilliant ok as always I'm YK

from CS dojo thanks for watching and

I'll see you guys in the next video