Learn Hash Tables in 13 minutes #️⃣

Hash Table tutorial example explained

#Hash #Table #Hashtable

// Hashtable = A data structure that stores unique keys to values
Each key/value pair is known as an Entry
FAST insertion, look up, deletion of key/value pairs
Not ideal for small data sets, great with large data sets

[BroCodez]

import java.util.*;

public class Main{

public static void main(String args[]) {

// Hashtable = A data structure that stores unique keys to values ex.<Integer, String>
// Each key/value pair is known as an Entry
// FAST insertion, look up, deletion of key/value pairs
// Not ideal for small data sets, great with large data sets

// hashing = Takes a key and computes an integer (formula will vary based on key & data type)
// In a Hashtable, we use the hash % capacity to calculate an index number

// key.hashCode() % capacity = index

// bucket = an indexed storage location for one or more Entries
// can store multiple Entries in case of a collision (linked similarly a LinkedList)

// collision = hash function generates the same index for more than one key
// less collisions = more efficiency

// Runtime complexity: Best Case O(1)
// Worst Case O(n)

Hashtable<Integer, String> table = new Hashtable<>(10);

table.put(100, "Spongebob");
table.put(123, "Patrick");
table.put(321, "Sandy");
table.put(555, "Squidward");
table.put(777, "Gary");

for(Integer key : table.keySet()) {
% 10 + "\t" + key + "\t" + table.get(key));
}
}
}

[Aussiesnrg]

Was a programmer on a statewide court system back in the late 80's that needed a surname search to return a full page of results in less than a second. We used hashing tables and progressive searches to keep the speed amazingly fast. I think we had it down to about 0.2 of a second.
They are fantastic with really large collections of data that needs searching.

[marius.y]

Hey Bro, I just wanna thank you for teaching me all this stuff. 7 months ago I was almost nowhere not even knowing how to write a main method in Java but now I'm programming my own graphics library. You're truly a legend😎

[WorkSmarter__]

Level of teaching of Bro is just on another level👍

[dmitriivlasov]

Bro, We just started going through Hash Tables in our CompSci class and now you release a video. Thank you!

[thomashansknecht]

I am surprised my computer science curriculum barely even mentioned hash tables. They have been such a game changer to me at work as a software engineer. Way faster and easier than using an array and nested loops.

[clashclans]

that actually makes so much sense!! was looking at the profssors notes and watching his lectures and not understanding it one single bit!!!! long live the BRO!!!!

[VERY_TALL_MAN]

Wow, this is a really good introduction to hash tables!

[crossfadez]

This was a very insightful video, thanks a lot. Although I really wished you also went over how to treat a bucket as a linked list and iterate through it to find the key you're looking for.

[hwstar]

Things to note:

If you have collisions the best course of action is to change your hash function. In your example, a good hash function would be taking the ascii code of the rightmost number and subtracting 48, that way you'd have 0 collisions and don't need to do % anymore.

Another thing, if your table size is a power of 2 you don't have to do % anymore, you can instead do bitwise and with table size.

[confused]

Oh My Goodness... The best video on HashMap data structure. You're the man! 👍

[AlexStampfl-fp]

Your videos are awesome, far better and easier to understand than my useless, confusing lectures, thanks!

[dbvs]

Thank you, I have been having questions on HashTable and wanted to understand hashCode, excellent explanation, keep doing more videos.

[PratikThisSide]

Simply, subtly & nearly explained Bro Sir 👌🏼
#KeelItUp ✌🏼 #LoveFromINDIA🇮🇳

[acatisfinetoo]

Hash table is my favoriate data structure😉

[oogshow]

It’s beautiful lecture I like this hash, I’m always favourite your lecture bro due to your best explanation, keep going bro

[ruleoflawedutainment]

I studied this last term but didn't understand what I do now. Thank you.

[patriciale]

I didn't pay attention during lecture and I have a quiz tomorrow, so this is a lifesaver!

[stephanieezat-panah]

As always, an excellent presentation. thank you

[nischalofchrist]

Bro, you Rock. Best and simple explanation of Hash tables. Thanks