Two Sum (LeetCode #1) | 3 Solutions with animations | Study Algorithms

Two Sum is a programming question on LeetCode and very important for interviews. You are given an array of integers and a target value as the input. There are exactly two integers in the array which add up to the target value. You are required to return the indices of these 2 integers. Watch this video to learn 3 ways of solving this problem. You will learn a brute force solution, a solution using sorting, and a solution using Hash-map. Each of the solution has been explained with step by step animations and with a dry-run of the code so that it sticks in your mind forever.

00:00 - Intro
01:07 - Problem statement and description
03:54 - Brute Force Method
06:03 - Method 1: Using Sorting
10:36 - Method 2: Using Hash-Map
14:04 - Dry-run of code
16:35 - Final thoughts

📚 Links I talk about in the video:

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#leetcode #programming #interview

[nikoo]

At 12:58, I am supposed to add "8" to the hash table and not "11".
Sorry for the error.

[halimaomar]

This is absolutely the best explanation on Youtube. Everyone else goes straight to coding and doesn't break down the logic beforehand.

[GHT]

this is my favourite channel for solving leetcode problems, i'm from Vietnam, thank you guy a lot

[Akash_XDD]

So nice of you to put this in a simple yet insightful manner, thanks a lot.

[billyfigueroa]

Excellent content. This is the second video I watch which allows one to be able to devise a nicer solution simply by sorting the array. The hash map solution is genius and is not complicated

I will now, always look at a problem and find out how I can solve it by first thinking "Would sorting this array help to simplify the solution"

[wenkaiyang]

thank you soooo much! I checked out so many videos about this question. finally your video helped me out! firmly subscribed to your channel

[Rockstar-]

Sir😄, I have no words, I have never seen anyone explain this nicley, thank you so much❤

[Spear_of_Boudicca]

Good video, very similar to my university lectures.

I think the reason a lot of people fail to learn some things on their own is that they just see code and want to understand it magically, you need to get the logic behind stuff.

[yowanehakuuu]

I watched two other videos before coming here, to be honest you are the best one . I only understand from you because other people talk too long without explaining they talk about the problem not the solution. You even taught me the math side of this . Thank you, I subscribed. I will watch the rest of the solutions

[Padmak-wl]

Bro you are just awesome.The best explanation so far. I am new to programming. It always scared to even touch leetcode, came across your channel somehow.. you just made it look so easy

[ayushtalks.]

One of the best way of teaching . Sir Keep posting more videos of dsa. 👍👍

[harihardhik]

Such a great way of explaining this problem. You have redefined teaching sir!!! Amazing Work!!!!

[pooja]

you are the best.I really appreciate your hard work and step-by-step approach to how to overcome with a solution. Hats off

[aman_rockstar]

you r really an excellent teacher one thing i want to tell ur explanation is better that striver thanks for providing such videos

[shacks-bb]

Please keep uploading DSA/leetcode videos, they all are really helpful, thanks!

[jst]

06:03 - Method 1: Using Sorting
This is basically sliding window solution, when you have two pointers, left and right and you move them correspondingly.

[joshuajacobs]

Only just got into coding a few days ago coming from a teacher background. Great explanations!

[elizabeth]

Thank you for taking the time to create this video and make a clear explanation

[sarthakgadge]

Thanks a lot, I was able to understand this problem thanks to your efforts.

[brahmithegod]

I was searching for the solution but do not found dryryn but u did it thank bro ❤️