just my opinion: 95% of Indian engineering students waste average 6 hours per day in colleges learning shit. We can easily understand actual concepts on youtube in 2 hours and through books for extra. Shit and lazy ass professors and money making colleges. Don't want to hurt anyone's sentiments but IT's THE F TRUTH. Thanks Tushar bhai. I am grateful to you.
I give you thumbs up because the same can be said for any field of study. But no employer is going to hire you to an engineering position without a degree. So the paper degree has its value.
I agree with you at some point. But college its also important because there professors guide students threw the most important subjects. If many people didnt go to college, this videos wouldnt be watched by the same amount of people.
I have never written comment on any video whether it is good or not, But your videos force me to write comment, By heart you are Genius man !!! Legend of Computer Science!!!!!
Tushar, these videos are phenomenal. It's very apparent that you have spent a lot of time preparing this material - your explanations and examples are incredibly clear. Thanks!!!
I can't put into words how much these videos help me and my friends understand the subject you cover! No way in a million years that my professor will go that deep into the explanation of the all the little (but very important) details you do explain. Please, please cover more topics in the future! :)
For the diagonal condition there is an alternate. Given two cells with the coordinates (i1, j1) and (i2, j2) , you can say they are on the same diagonal if | i1 - i2 | = | j1 - j2 | . You can validate this by calculating with values, or you can deduce it from the two formulas you have stated. This way you only need a single formula to validate if the queens attack on diagonal.
You can deduce this with the slope of the line formula Y2 - Y1/X2-X1 = +1 or - 1 implies that the angle is either 45 or 135 degrees and hence is a diagonal
I have seen most of your videos and just wants to say a big thanks. you are a role model for many young people coming out and wants to achieve something big in their life....
Thanks.. A Suggestion- You could simply check if mod(row1-row2)== mod(col1-col2) to check for the diagonal attacking position rather than using 2 separate formulas for 2 diagonals.
Hey, which part of you code does backtrack? I think somewhere you have to remove the elements from position when its not safe. I can't get that part in your code. Can you explain
I got the same doubt and tried to understand that piece of logic. Looks like, the elements won't get removed as such from Positions, they rather get replaced/updated by a new element in the next iteration.
hey i don't know about of number of views people have got in their video for explaining N queens problem. But i tell you people this is the best explanation. NOBODY by far can teach in such a simpler way as he has done. You have any tutorials for all this Tushar, i would love to join it.
This is an awesome explanation. Helped me understand backtracking. And all the people telling you that your english is horrible do not deserve your attention. Fuck 'em
Thanks sir..Its very good explaination. One problem : when we are backtracking we should delete element from position array. if(solveutil) return true; else delete pos; ...... return false;
Here's a more elegant explenation: ruclips.net/video/R8bM6pxlrLY/видео.html&feature=share&fbclid=IwAR3Sl96wOacXpuifjl3syZJv8foyH4z_TENM-Q6k75SPTSvEybSb6n9KrG8
Thanks for the videos, they are great! Keep up the good work!! I went through this code which says it is of Time: O(n*n) but actually, it's of Time: O(n*n*n) because you fix rows (Time: O(n)), increment col for every row (Time: O(n)) and check for positions for every col which again is another Time: O(n). All of this adds up to Time: O(n*n*n). Please check and correct it.
If they gave me a problem in real time I can solve it with the basic serial and according to the family that belongs to the board. This is only for cases of an empty board. For the case of a board with a queen on the board, I can solve all the prime boards in the position that the queen is indicated, be of the size that is from n = 5, 7,11,13,17,19,23. ........ 61, ..... etc
I noticed that in the code example you have the space complexity as O(n*n), however, isn't it O(n) where n represents the total number of queens we have?
The tree visual was fantastic. It allowed me to visualize how the algorithm was eliminating possibilities and backtracking to the first level to start over.
Thank you Tushar! Your explanation is really clear and makes sense. It saves me tons of time and makes my day! I hope you can continue to upload more videos.
Very clear cut explanation of n Queen problem. Thanx a lot Sir. Please upload the videos on bellman ford with directed graph with algorithm. Sir it is very hard to understand. Please Sir help me In this.
There are a lot of obviously unnecessary check that could be avoided: the four squares around each queen are for sure not safe so why even try it? I would create N square object with a queen property that holds the queen id if attacking it. After each queen position iteration I would jump to a square that is not already attacked by a queen and place the queen and register her id to all squares it attacks. So after each iteration the number of available unattacked squares will reduce and makes the the algorithm finish much faster.
Awesome video, thank you so much. If I may suggest, it might be better if you can also use a mic for the white board explanation since the sound quality will be much better.
Can you please make a video on "How to make recursion tree" and thinking of solving it recursively, i often confuses when i see two or more functions calling to same functions again and again.
Thank you for making me understand Recursion.....What I have got from your explanations is something very valuable....I got to learn the concept of Recursion, Back Tracking and Dynamic programming. After understanding the concept, I am able to code it myself. Thank you
big thanks for making such amazing videos. It'd be of great help if you do a video on GRAPH COLORING (Using Backtracking). Please. Thanks in advance. :)
Awesome video, very well explained. I think that I would now be able to solve this exercise even a little later in the future, as I have understood the principle and the rules to determine a valid placement for a queen. One question regarding the backtracking step though: If a callee function return false to the caller, that's to say a deeper level of recursion can't find a valid place for a queen, the calling function continues to look for a valid place one column ahead where it stopped before. However, the previously placed queen in the array is never cleared and remains there. Doesn't that cause problems? On the right hand side you always remove the notes but you don't do it in the code. WOuldn't you have to add an else statement after the if(foundSafe) block to remove an falsly placed queen?
Hello m8! I was expecting another kind of solution. I really appreciate your video and i would like to say thank u. But, i think that we could work in a faster solution
Awesome explanation. You inspired me to make my own version of this video for explanation.
And actually you made it!
Great video man!
Is Rajesh Koothrappali ur bro?
lol
Which of the following data structures is used in backtracking algorithm?
A: Queue
B: Stack
C: AVL Tree
D: Skip List
Row 0 Column Thoo
just my opinion: 95% of Indian engineering students waste average 6 hours per day in colleges learning shit. We can easily understand actual concepts on youtube in 2 hours and through books for extra. Shit and lazy ass professors and money making colleges. Don't want to hurt anyone's sentiments but IT's THE F TRUTH. Thanks Tushar bhai. I am grateful to you.
I give you thumbs up because the same can be said for any field of study. But no employer is going to hire you to an engineering position without a degree. So the paper degree has its value.
I agree with you at some point. But college its also important because there professors guide students threw the most important subjects. If many people didnt go to college, this videos wouldnt be watched by the same amount of people.
I have never written comment on any video whether it is good or not, But your videos force me to write comment, By heart you are Genius man !!!
Legend of Computer Science!!!!!
thanks for writing the comment for the first time.Now i can die peacefully.
Tushar, these videos are phenomenal. It's very apparent that you have spent a lot of time preparing this material - your explanations and examples are incredibly clear. Thanks!!!
Great Explaination Tushar. Kindly consider doing the Graph Coloring problem using backtracking as well!
I can't put into words how much these videos help me and my friends understand the subject you cover!
No way in a million years that my professor will go that deep into the explanation of the all the little (but very important) details you do explain.
Please, please cover more topics in the future! :)
For the diagonal condition there is an alternate. Given two cells with the coordinates (i1, j1) and (i2, j2) , you can say they are on the same diagonal if | i1 - i2 | = | j1 - j2 | . You can validate this by calculating with values, or you can deduce it from the two formulas you have stated. This way you only need a single formula to validate if the queens attack on diagonal.
Totally agreed. Taking absolute of " |X2 - X1| == |Y2 - Y1| " is better conditional statement for checking if the queen is safe or not.
You can deduce this with the slope of the line formula
Y2 - Y1/X2-X1 = +1 or - 1 implies that the angle is either 45 or 135 degrees and hence is a diagonal
I have seen most of your videos and just wants to say a big thanks. you are a role model for many young people coming out and wants to achieve something big in their life....
Thanks.. A Suggestion- You could simply check if mod(row1-row2)== mod(col1-col2) to check for the diagonal attacking position rather than using 2 separate formulas for 2 diagonals.
No bro
You will have to use two conditions in that case too
yeah
Isn't the time complexity O(n!)??
Best explanation I have seen yet. Thank you!
What is the time complexity of this problem?
wow. clear as water.
The legend of Computer Science. Yesterday I had lots of problems regarding coding a solution for this problem, now I don't have any. Brilliant video!
Hey, which part of you code does backtrack? I think somewhere you have to remove the elements from position when its not safe. I can't get that part in your code. Can you explain
I got the same doubt and tried to understand that piece of logic. Looks like, the elements won't get removed as such from Positions, they rather get replaced/updated by a new element in the next iteration.
was wondering if someone could elaborate on time complexity of algorithm
Any trick to make this code to get all possible solutions?
is there any solution
best video available for the N queen problem using backtracking .
A big thaanks dude!!!!!!
hey i don't know about of number of views people have got in their video for explaining N queens problem. But i tell you people this is the best explanation. NOBODY by far can teach in such a simpler way as he has done. You have any tutorials for all this Tushar, i would love to join it.
This is an awesome explanation. Helped me understand backtracking. And all the people telling you that your english is horrible do not deserve your attention. Fuck 'em
I've written a small article to explain this topic. Hope you find it useful! @ www.thecodenote.com/2017/05/beginners-guide-to-solving-n-queens.html
Is it easy or difficult to find one pattern (one solution) of 2500 or 5000 queens with Backtracking Algorithms?
Very helpful! Thanks for sharing
very good by far the best explanation for this problem the explanation of index of attacks was very very helpful
Thanks sir..Its very good explaination. One problem : when we are backtracking we should delete element from position array.
if(solveutil)
return true;
else
delete pos;
......
return false;
you alright bro? you got the thousand algorithm stare goin
Good Explanation. Helped me to understand the problem easily. Thank You.
Tushar roy : How Does a Queen Attack?
Me : By Marriage
😂😂😂😂
Hope your wife doesnt read this
@@adhishmalviya2408 i am single
😁😁😁
Thoroughly explained! I love this! Thank you for your video!
Greatest explanation (for me). Thank you so much
Here's a more elegant explenation:
ruclips.net/video/R8bM6pxlrLY/видео.html&feature=share&fbclid=IwAR3Sl96wOacXpuifjl3syZJv8foyH4z_TENM-Q6k75SPTSvEybSb6n9KrG8
Garcia Brian Gonzalez Mary Walker Jeffrey
can you link to the chessboard visualizer?
thanks Tushar Roy, your videos are really helpful
can you explain how backtracking is happening here
Great video , again !
Could anyone tell me what is the visualization tool he is using?
Hi thank you. Can you explain with bishop?
Anyone who's watching in 2024!
Great Explanation. the best one on n-queen problem.
Thanks very much！！！
Thanks for the videos, they are great! Keep up the good work!!
I went through this code which says it is of Time: O(n*n) but actually, it's of Time: O(n*n*n) because you fix rows (Time: O(n)), increment col for every row (Time: O(n)) and check for positions for every col which again is another Time: O(n). All of this adds up to Time: O(n*n*n). Please check and correct it.
If they gave me a problem in real time I can solve it with the basic serial and according to the family that belongs to the board.
This is only for cases of an empty board. For the case of a board with a queen on the board, I can solve all the prime boards in the position that the queen is indicated, be of the size that is from n = 5, 7,11,13,17,19,23. ........ 61, ..... etc
You are a hero at explaining things.WELL DONE SIR.THANK YOU SOOOOOO MUCH.
I noticed that in the code example you have the space complexity as O(n*n), however, isn't it O(n) where n represents the total number of queens we have?
The tree visual was fantastic. It allowed me to visualize how the algorithm was eliminating possibilities and backtracking to the first level to start over.
Thank you Tushar! Your explanation is really clear and makes sense. It saves me tons of time and makes my day! I hope you can continue to upload more videos.
Hi Tushar, In your N-queen video, you said the time complexity is exponential but your github comment has time complexity as n2.
Very clear cut explanation of n Queen problem. Thanx a lot Sir. Please upload the videos on bellman ford with directed graph with algorithm. Sir it is very hard to understand. Please Sir help me In this.
goob expolntn love frm pakistan
sir plz explain about GRAPH COLORING using backtrack
can you write an implementation of mazes game using c language
I've watched 3 videos prior to yours' on this topic and so far you've done the best job explaining it. Thanks.
There are a lot of obviously unnecessary check that could be avoided: the four squares around each queen are for sure not safe so why even try it? I would create N square object with a queen property that holds the queen id if attacking it. After each queen position iteration I would jump to a square that is not already attacked by a queen and place the queen and register her id to all squares it attacks. So after each iteration the number of available unattacked squares will reduce and makes the the algorithm finish much faster.
The best explanation for backtracking..........!!!!! thanks tushar... :D
Awesome video, thank you so much.
If I may suggest, it might be better if you can also use a mic for the white board explanation since the sound quality will be much better.
When we backtrack shouldnt we clear the previously set foundSafe position in the positions array?
it is very helpful sir...can please explain global parallel genetic algorithm for solving n queen problem n also naive algorithm for n queen
This is the best explanation I got yet.
can you tell me 6 Queen's problem?
Can you please make a video on "How to make recursion tree" and thinking of solving it recursively, i often confuses when i see two or more functions calling to same functions again and again.
Thank you for making me understand Recursion.....What I have got from your explanations is something very valuable....I got to learn the concept of Recursion, Back Tracking and Dynamic programming. After understanding the concept, I am able to code it myself. Thank you
can you help me ; i have an exercice ; last letter first letter problem ; i dont understand how i use backtracking thanks
Only if Engineering Colleges in India hired teachers like you, we would not have to watch this video.
You are amazing. I code in python but the way you explain your code is so good. Thanks : )
Agree with others. Your explanation made so much sense. Great job.
Your explaination is always clear and easy to understand! Thanks for your videos!
If anyone's struggling with the indices for the diagnols think of straight line equations but this array is in the 4th quadrant
what if i fixed 2 queens in 8 queen problem , then how many solutions exists in 8 queen problem?
Great Work, a neat and simple solution,
is there any other solution possible for Nqueen problem with lesser timeComplexity.
big thanks for making such amazing videos. It'd be of great help if you do a video on GRAPH COLORING (Using Backtracking). Please. Thanks in advance. :)
Can anyone tell me why Tushar has taken 1 box for row 0, 2 for row1, 3 for row 3 and again two for the last row?
May 2021 LC challenge anyone?
What if don’t know how many queens can fit on the board? Or is it assumed as part of the problem
Awesome video, very well explained. I think that I would now be able to solve this exercise even a little later in the future, as I have understood the principle and the rules to determine a valid placement for a queen.
One question regarding the backtracking step though: If a callee function return false to the caller, that's to say a deeper level of recursion can't find a valid place for a queen, the calling function continues to look for a valid place one column ahead where it stopped before. However, the previously placed queen in the array is never cleared and remains there. Doesn't that cause problems? On the right hand side you always remove the notes but you don't do it in the code.
WOuldn't you have to add an else statement after the if(foundSafe) block to remove an falsly placed queen?
I would be nice if coding is explained a bit clearer. Thanks anyway.
Can you zoom the algorithm section? . it would be much helpful
sir could u also.make videos on graph coloring and hamiltonian problems
but in the second row queen off diagonal is going to attack by first row queen!!
Please can you make a video on 8 puzzle problem using A* search.
hey! looking for the python code of this algorithm ... Any help please ?
What about the 8 queen problem? Can your code be scaled to larger problems?
thanks a lot for your clear and brief tutor and it insight me about this topic thanks again keep go on
Very good and clear explanation. Thank you for the video.
this is a great video. Always helps me a ton to see stuff drawn out like this.
You can keep a Map for the finding how many queens are attacking a row, column or diagonal and check if the current cell is under attack or not
Hello m8! I was expecting another kind of solution. I really appreciate your video and i would like to say thank u. But, i think that we could work in a faster solution
I like your explanations but I find it really hard hearing you. Kindly work on your audio
sir, can i get the above code in C++, i would be very helpfull if u can do it
i saw your lots of videos which helps me a lot do as many as possibles plz...
I watched many backtracking videos, but this is so simple and understandable. thank you man
can u show give the solution tree/space tree for n queen problem?
concise explanation. understood the use of row + i, row - i .
Loved this solution!! Your solution is amazing.. would be better if you had explained time complexity, why it is exponential.
Appreciate your hard work. Very well explained.