Implementing Recursion Ideas into Code | Day 1 Part 2 | Dynamic Programming workshop | Vivek Gupta

[@codingwithanonymous890]

that diagonal check using absolute value of previous and current row/column was mindblowing...O(1)

[@amandixit8342]

yeah beacause ek hi loop mein teeno possiblities check kar de raha , jab mene ye dekha 2-3 friends ko aur batya dekh bhai aise b ho skata no need to 3 loop for checking , it's really good approach :)

[@harshupreti1526]

Yes checking of the slope

[@soumyadeepdash4805]

You can also do the whole check function in O(1) using three arrays, 1st array is to check whether we can place the queen in this column, 2nd one is for left diagonal and 3rd is for right diagonal. Indexing of left diagonal => n-row+col,,,, right diagonal => (2*n-1)-row-col. Also u have to update these arrays when placing queens.

[@vivekgupta3484]

@@soumyadeepdash4805 True. infact even faster approaches exist like keeping this diagonals in bitmask and taking & to find possible positions in O(1) ... thats even faster... but let's keep things to limit for now.

[@radicalengineer2331]

This is one of the most optimal ways to solve with a framework bhai ko as if pata hai ki exactly kidhar we'll get stuck and he has shown us the way to think on that using his LCCM method Super bhai

[@utkarshpandey6600]

diagonal trick is came from mathematiics slope formula, as we know diagonal are at an angle of 45 degree , so tan 45 is 1. then our formula will become like that condition

[@AmanTheMystery]

that diagonal check trick is awesome....that why if some one knows recursion still i said to watch vivek sir videos u will get new things in your bag

[@CodeChamp-tw8ho]

great problems and a lot to learn!!💻💻

[@anjumankhan1593]

Super easy to understand with LCCM method!!!

[@CREATIONTIME1]

why this video is not getting millions views.. this is the best explanation..

[@abhishek04204]

dont know how you manage the recording and your job thank you for the videos

[@Sandeep-zd6dq]

Loved this video, specially the check to place the queen till now I was always writing 3 loops in my check function 😂

[@akshatmehra3951]

Maze aa gye bro 🔥N-Queens ekdum samajh aa gya. Thanks a lot for the good work, keep it up 👍🏼 full support

[@socify4410]

absolute mindblowing

[@leftover19]

Hii sir, my friend gave me your algozenith course and another friend (6* on codechef) told me to learn dp from here. When I heard your voice i was like 🤯🤯 this man. All I want to say is your explanation is very elaborate and easy to understand. Never understood dp this way. Thanks for the effort.,❤️

[@noone0978]

note for me: see, the approach i can think for last problem is that we will declare penalty as global variable starting from zero, then we will write the rec function with level starting from zero and going till n and we will declare n as k+1, we will also make an array of size k+1 which will store the area of each part because k tear will result in k+1 parts, when the base case will hit that is level==n, then we will find penalty=min(penalty, current penalty) where current penalty will be sum of square of elements of array, now for the tear part that how we will tear, what i thought was we will use two recursion loops, one will tear horizontally and other will tear vertically this is not complete but this was my first thought hit in 2 minutes after seeing the problem

[@Sandeep-zd6dq]

Bro ye shi tarika hai video ko question k saath end krne ka 😂 ab ruka hi nhi jaa rha isko solve toh krke rahunga 😎 because it’s a new question for me 🔥

[@AshishKumar-cw9xw]

Can u please send the solution of last problem

[@AdityaPradhan-f2p]

24:05 Wow!

[@smile_please5848]

can anyone explain what we are doing at 22:49 ,how we are saving the position of previous queens?

[@vivekgupta3484]

the queens array is global and is being shared across … and in recursion it is being filled

[@sachitsankhe5102]

Amazing Day-1

[@saranghae3720]

last problem is based on dp on partition, as we can cut at any co-ordinate of the grid. Correct me, If I'm wrong.

[@akshayshah7008]

Hey Vivek, Everytime writing the base case first is necessary or how do you think when it comes to base cases?

[@ArnabJhaYT]

very beautiful code

[@shriyanshjain4444]

33:18 I understand the logic explained but line 38 and 40 inside if check confuses me still. Can anyone help?

[@abhishekc3556]

Line 38 is suppose if you've placed a queen at the current level / row you're at, then you do rec(level + 1) meaning after you've placed the queen at current row, you're asking the recursion to go to the next level / row and place queens there if possible. Line 40 is suppose you have a 8*8 board and you place a queen on the 0,0 coordinate. Assume the total number of possible configurations is x if you've placed the queen on the 0,0 coordinate. Now the question wants you to compute the total number of cases right. So now you'll place a queen on 0,1 coordinate and try to find all possible configurations but before you place a queen on 0,1 you need to remove the queen you had placed on 0,0. That's why on line 40 we remove the queen that was previously placed

[@abhishekc3556]

I'd recommend to go through striver's recursion playlist. He's explained recursion beautifully

[@MCAAARULMishra]

@@abhishekc3556 can you please explain why he said LINE40 is not need for this problem at 26:34

[@shriyanshjain4444]

@@abhishekc3556 sure will check that

[@abhishekc3556]

@@MCAAARULMishra just watch takeUForward's nqueen problem once and even then if you don't understand, I'll explain.

[@AKASHKUMAR-li7li]

in que 3 why we have not taken the values itemTaken and timeTaken along with recursive calls.....?

[@Profnegi]

N-queen best: i've done this by myself after watching the video (in leetcode there is more on this problem )

[@utkarshpandey6600]

i 3rd question , how ans will return our real maximum skill, in whole code we do not did anything to it. and how answer return.

[@vivekgupta3484]

Time stamp exactly?

[@noone0978]

in 3rd problem that skill one, you didn't used loop, but can we iterate over all n and then check if it satisfies or not instead of using 2 recursive calls, like one for loop and one recursive call inside that for loop?

[@Abhishek-fo3fc]

DAY 1 PART 2 DONE

[@dharsan.s7937]

Solved all the practice problems

[@AshishKumar-cw9xw]

Can you please send the last problem solution

[@Dr.dhumketuIITDholakpur]

can you please send link of last question that X time and K problem one

[@priyojitghosh3672]

not able to open the question link

[@vivekgupta3484]

Make sure to signup on learning.algozenith.com

[@abhi_3158]

bhaiya can u decrease the font of the code so that we can see the all the code of one function in one time so that we can get the intution of the function more easily.Overall your content is amazing.

[@ZSTAR_CODE]

NQueen backtracking 20:00

[@hello-sb7zj]

Can anyone tell what is the time complexity of example 3

[@vivekgupta3484]

Let's discuss time complexity in today's Live class.

[@hello-sb7zj]

@@vivekgupta3484 ok sir

[@PrasadTGS]

Is it possible to watch the live class now @@vivekgupta3484

[@codemode2925]

need some more calrity on the reverting the choices part.

[@abc-ym4zs]

bhaiya i dont why i am afraid of doing new things how to comeout of this way

[@PrasadTGS]

why did we take queens array size as 20 , dont it effect in case of large board

[@SRoy2700]

yes if the board size is > 20 *20 then it would definitely

[@jayantgupta5310]

Problems page is showing error 404 not found

[@vivekgupta3484]

sorted now

[@niveditashukla2901]

bhaiya, I solved this count number of ways to climb stairs on an online coding platform but it showed TLE for some test cases!

[@vivekgupta3484]

Great … check comments … not everything is DP ;P

[@akshatsinghtomar9207]

Isn't 3rd question a greedy problem?

[@nitinchoudhary5183]

could you please help to model “find all substrings of a input string” in level , choice , check , move framework

[@vivekgupta3484]

Do you mean distinct substring? that is a from 2 problem ... we will discuss it don't worry.

[@sababmuhammad4842]

understood

[@nikhilkumarv2577]

🛐

[@yashmohta6420]

Bhaiya problem link is not working ,please do something about it.

[@vivekgupta3484]

sorted now

[@Sandeep-zd6dq]

In skill problem can we avoid that check if we keep timeTaken and itemTaken in our recursion states ??? Although not sure🤔 But this check enforce us to follow this structure 🙌

[@vivekgupta3484]

Correct.. that's what we are actually gonna do ! Great observation.

[@rachakondaeshwar4129]

N queen is now easy

[@aryanbarnwal5645]

problem link not working

[@vivekgupta3484]

new course added

[@shivankkunwar9669]

the videos are great but the algozenith platform is impossible to write code in java worst experience .

[@vivekgupta3484]

you are supposed to write in your own pc .. test and paste

[@shivankkunwar9669]

@@vivekgupta3484 💁💁💁💁

[@AmanChauhan-hr1wh]

ans=0 then ans+=...is confusing can anyone explain that part plss

[@hritikrawat6452]

May I know how we can verify 92 moves answer is correct or not?

[@vivekgupta3484]

Because i got the same :D

[@enigmanarratives1]

how much tym will it take when i will be able to solve leetcode medium fast and without liiking solution i am 90 at leetcode

[@vivekgupta3484]

300 - 400 problems

[@ashokcherry8015]

I am from banglore

[@ashokcherry8015]

Bhaiyya meet up

[@vivekgupta3484]

Neend hi muskil se ho rhi hai kabhi kabhi... thoda aur ruk jao... par pakka karenge.

[@jivanninawe3190]

Bhai hindhi may banaho video

[@DPCODE72]

Heyyyy bro....small advice go with Hindi language!!