Data Structures & Algorithms #1 - What Are Data Structures?
Summary
TLDRIn 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
📚 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.
🛣️ 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.
🎉 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.
🚀 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.
Mindmap
Keywords
💡Data Structures
💡Algorithms
💡Software Developer
💡Google Maps
💡Latitude and Longitude
💡One-Way Streets
💡Arrays
💡Hash Tables
💡Shortest Path
💡Efficient Software
💡Brilliant.org
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
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