6.1 N Queens Problem using Backtracking 

It has been 5 years but still these videos are better than new ones by other youtubers.....i am referring to these in 2023...thank you sir

*I am from ECE Background, trying my hard for product based companies and I want to thank Sir Abdul Bari for all the Concepts which helps me in competitive programming*

thank you for all your lectures, you are like a god sent to us.

Abdul Bari Sir I just wanted to thank you. I have successfully completed my M.Tech with good CGPA and yeah topped at college level. You contribute a lot to my grand success. Thanks a lot. But I regret for I could not find your videos during my B.Tech. Anyways, ALHAMDULILLAH. Now watching your videos to prepare for teaching demos.

You are the best teacher of algorithm in RU-vid

Ok i can Proudly say that He was my lecturer At College ❤️

That's great contribution Professor! Everything in the presentation is superb - contents - speed of delivery - board usage - selected examples Everything Hats off to you Sir 🙏

A simple way to explain the N queens problem & solution, love it! Greetings from France

Thank you. One of the best description on Backtracking, and its difference with Dynamic Programming.

i'm currently watching to save my self from failing my class thank you

Great ! You are a great Teacher. Thanks for saving my Design and analysis of Algorithm Paper. #Respect

You are so good at explaining this. Thank you so much for your time!

exceptional articulation sir. I myself get's confused going through it step by step while you're able to trace it accurately for each node. Really inspiring.

Thank you so much for your videos! I am trying to self-learn competitive programming and your videos are a great help to so many students around the world! Keep doing what you do best!

Thank you Abdul Bari sir for your videos on Algorithms. They are helping a lot of students like me. Your work is very much appreciated.

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Everytime i used to watch your lectures but never bothered to comment...but sir you way of teaching is superb! Thank you for your lectures.

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Well Explained the Solutions .. specially that mirror image of last vedio footage 13:30 ... Thanks Sir

Thank you,Sir.You made the searching problem easy to understand.

Very nicely explained! And not too hard English used 😋

sir love your videos...kindly consider including the algorithms along with the explanation

I have done crazy amount of practice finally I understand it perfectly. keep doing practice you are going to master it.

Your explanations are super clear. Can you add videos about topological sort, strongly connected components, and bipartite graphs?

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Made the problem easier well done Great privilege to see this

Thank you sir for clearly explaining step by step

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@Abdul Bari Sir, your explanations are so amazing!!

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Great Sir. Clear explanation. Thank you so much Sir.

Really helping your videos alot professor.. Thank you

n-Queens Python: class Board(object): def __init__(self, n): self.n = n self.board = [[0 for _ in range(n)] for _ in range(n)] def solve(self, row, result, output): if row == self.n: output.append(result[:]) return for col in range(self.n): if self.isSafeCell(row, col): self.board[row][col] = 1 result.append((row, col)) self.solve(row+1, result, output) self.board[row][col] = 0 result.pop() def nQueens(self): result = [] output = [] self.solve(0, result, output) return output def isSafeCell(self, row, col): # Vertical check for r in range(row-1, -1, -1): if self.board[r][col]: return False # Main diagonal check r = row - 1 c = col - 1 while r >= 0 and c >= 0: if self.board[r][c]: return False r -= 1 c -= 1 # Minor diagonal check r = row - 1 c = col + 1 while r >= 0 and c < self.n: if self.board[r][c]: return False r -= 1 c += 1 return True def display(self): for row in self.board: print(row) b = Board(4) b.nQueens()

thank you so much for all your videos, major help!!

Very great explanation. Thanks sir, you earned my respect

Hi sir I saw the video of n queens problem ,it helped me lot to create my own presentation Now I am in need tug of war problem using backtracking

I love ur way of teaching sir.u makes the lesson easy.Love from bangladesh.

without your lectures we are wasted sir♥️♥️💯🔥

Thank You for explaining it so well! :D

Brilliant explanation. Thanks, Professor Abdul!

Thank you master you're the best explaning👍

very good explanation. very helpful

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Thanks sir... U gave us THE BEST lecture

Note that the reason you're able to restrict the first queen to the first row, second queen to the second row, and so on is because they are all queens, so it doesn't matter which queen is on which row -- they will all function the same way. In other words, the ordering of the queens doesn't matter. You could just as well put queen 3 in row 4 and queen 4 in row 3 and achieve the same result. We are forcing there to be a single queen per row, since otherwise two queens would be under attack, and are just interested in specifying which _column_ the queen in each row will be on.

Thank you sir for such great explanation!!

Amazing sir Understood in a single go

wow.. It's really fun. I'm not good at English but this lecture is easy to understand. I already know backgrounds, but it's very fun to me. now i'm conside buy ur other lecture.

What a great way of explanation. Thank you so much Sir G

Thank you so much sir this concept is really easy but my sir can't explained in depth..

Nice Explanation...Thank you sir

Very Good Explanation. Very Helpfull

Don't know what I'd do without you!!

You are excellent teaching in DDA subject TQ sir

Explanation is awesome but please add programmatic pseudo code also

After the first arrangement of all the queens,shuffling of q3 was done and so was done for q4. As q4 was already in 4th column why you have written q3 in 4th column?

This guy teaches a million times better than my gibbering algorithm teacher.

sir we are back benchers so sorry for this meru explain chesey way ke okkati chpali sir me modda ke salam me gudha ke gulham hattsoff sir for passing out in this subject

Dear Guru...! Its very great that you've explained well .but we as a learners we'd also expect it in Algorithm tracing .if you possible could you please make it out sir

Sir, you are really great. Thanks sir

superb explaination in simple words

Excellent sir...Thank you very much...

Thank you sir very nice explanation...

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Very good tutorial. Very systematic

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wonderful teacher u r ..........sir most of the student try to study cormen book of algo but failed to do so ......sir plz make videos of cormen book explanation .........it will be of grt help to many..........thanks

Loads of respect sir and thank you very much sir

You are an Inspiration sir✨

*3 things to worry about so queens don't attack each other: same row, same column, and same diagonal *generate a state-space tree *the default is that the nth queen is in the nth column and nth row (they form a diagonal on the board from left to right) the state-tree backtracking starts at 8:40 Thanks for the video!

well explained......thank u sir jii

Like -> Watch -> Practice -> Repeat

Such a great way of explaining the QueensProblem ... Thanks a lot!

Thank you, great explanation!!

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Great explained, thank you

First year here, this was extremely helpful!

Great explanation!

my favorite teacher on utube

Excellent explanation. Thank you.

Thank you very much sir I have clear this subject in just two days before exams👦

Thank you very much sir for so easy explaination.

Sir, I suggest you to make comments about the complexity and algorithm/program for each problem, in that way it will present complete discussion about a problem otherwise students need to search other content for getting answers to these questions. Thanks!

Thank you for a great explanation in a short time.

You are the best teacher sir

Sir, can you please show the steps to find the time complexity using the recurrence relation T(n) = nT(n-1) + n^2

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Great explanation.. Please could you also add the pseudo code and explain it

very nice explanation sir