L19. Rat in A Maze | Backtracking

  Рет қаралды 201,267

take U forward

take U forward

3 жыл бұрын

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Пікірлер: 292
@takeUforward
@takeUforward 3 жыл бұрын
✅ Instagram: instagram.com/striver_79/​ Please like and leave a comment if you understand, a comments means a lot to me :)
@ScienceSeekho
@ScienceSeekho 2 жыл бұрын
class Solution{ public: vector ans; void solve(int i, int j, vector &m, int n, string ds) { if(i < 0 || j < 0 || i >= n || j >= n || m[i][j] == 0) { // if we are beyond boundary / current is blocked = 0 return; } if(i == n-1 && j == n-1) { // If we reached the end ans.push_back(ds); ds = ""; return; } m[i][j] = 0; // set current visited so it wont picked up next time solve(i, j+1, m, n, ds + "R"); solve(i, j-1, m, n, ds + "L"); solve(i+1, j, m, n, ds + "D"); solve(i-1, j, m, n, ds + "U"); m[i][j] = 1; // backtrack it to 1 } vector findPath(vector &m, int n) { string ds = ""; if(m[0][0] == 0 || m[n-1][n-1] == 0) // If we cannot start at first position or end return {}; solve(0, 0, m, n, ds); return ans; } };
@memesdarbar6493
@memesdarbar6493 Жыл бұрын
Bro pls speak in hindi because sometimes I don't think what you tell.
@vrashankraom
@vrashankraom 3 жыл бұрын
Neither coding blocks nor coding ninjas courses worth rupees 10k can match this type of explanation. Hats off
@ragul6356
@ragul6356 2 жыл бұрын
Indeed
@verizon2851
@verizon2851 2 жыл бұрын
True!
@nopecharon
@nopecharon 2 жыл бұрын
I have taken both the courses and believe me Striver, aditya verma and mycodeschool are just killing it. No paid content can compare to there approach of explaining
@karthikeyan1996_
@karthikeyan1996_ 2 жыл бұрын
Scaler 3.5 lakhs u missed it bro
@ScienceSeekho
@ScienceSeekho 2 жыл бұрын
I did the 4K coding ninja course now watching this 🙂
@saketsharma133
@saketsharma133 Жыл бұрын
If anyone is wondering that in GFG the required TC is O(3^(N^2)). But here Striver has calculated it as O(4^(N^2)). Then, Striver has taken 4 choices at each point in matrix - D,L,R,U. But, in essence, there are only 3 choices. The place from where the mouse has came, it can not go back at that same place back. This eliminates 1 choice and leaves us with only 3 choices.
@immortal4412
@immortal4412 Жыл бұрын
right perfect!
@sameeksha5309
@sameeksha5309 10 ай бұрын
While backtracking, when I move to (3,1) from (3,2), the vis[3][2]=0, then how come we don't move back to (3,2) again since that position has been made unvisited during backtracking?
@shailesh_rajpurohit
@shailesh_rajpurohit 4 ай бұрын
@@sameeksha5309 because you are backtracking at the end of solve function from where you can not go to previously visted. Try to make a function tree and then you'll get it.
@ashtonronald
@ashtonronald Ай бұрын
good observation!
@shashikantmony7844
@shashikantmony7844 2 жыл бұрын
Thank you Striver, for the recursion series, I was really afraid of recursion, and the problems like Sudoku and N Queen used to haunt me. But not anymore. Thanks Striver
@elements8630
@elements8630 Жыл бұрын
Same
@iWontFakeIt
@iWontFakeIt 2 жыл бұрын
your explanation is so good that now i am writing code by myself, just watching the first 5-6mins of your video gives enough idea to approach the problem, though i am taking a bit longer to write the successful code, but writing it with my own understanding gives immense confidence to solve more! Thanks!!!
@saketsharma133
@saketsharma133 Жыл бұрын
Yes, absolutely right
@skilz9525
@skilz9525 Жыл бұрын
can relate 100%
@parthsalat
@parthsalat 2 жыл бұрын
The best part is that he taught us the brute force solution and then optimised it! I'm gonna do the same thing in the interview!
@skilz9525
@skilz9525 Жыл бұрын
This series is absolute bonkers!!! U have taught us so well that just looking at first few minutes of the video I was able to solve this on my own without even looking at the pseudo code. Just cant thank you enough bro
@shinewanna3959
@shinewanna3959 Жыл бұрын
After ur past tutorials, I did solve this problem by myself without watching the video, thanks to u for the best teaching. I love u bro. If u r right behind my side, I'll run towards u and will give u a big hug.
@fmkhandwala39
@fmkhandwala39 Жыл бұрын
After watching 18 videos so far, I was able to come up with the pseudo code myself for first time before watching the video. All because of your teaching. Cannot express in words my gratitude. Thank you!
@laxminarayanchoudhary939
@laxminarayanchoudhary939 2 жыл бұрын
Seriously, I really want to thank you from my heart for your efforts brother. Because after a break, i was thinking where to start for interview preparation and you are the one whose one of the video came up and I started following your series.
@amanbhadani8840
@amanbhadani8840 2 жыл бұрын
Loved your approach of solving questions,crisp and clear code.Enjoyed watching this recursion playlist.
@iamnehanupur
@iamnehanupur Жыл бұрын
Thank you so much! I have been trying to understand this problem for a long time. Your explanation just made me understand the concept behind this problem.
@kishoregovindaraj7165
@kishoregovindaraj7165 Жыл бұрын
Thank you Striver, for this amazing series. I had more confusions in recursion but this series made me feel, I can do the recursion problems easily.
@navendraagrawal
@navendraagrawal 2 жыл бұрын
instead of using the visited vector we can also do m[i][j]=0 before another recursion call and m[i][j]=1 after that call
@suchitrandas7380
@suchitrandas7380 2 жыл бұрын
But that will alter the given matrix probably , isn't it?
@navendraagrawal
@navendraagrawal 2 жыл бұрын
No while backtracking we can again set its value to be 1 so it will not alter the matrix
@ScienceSeekho
@ScienceSeekho 2 жыл бұрын
Yep. Thank me later. class Solution{ public: vector ans; void solve(int i, int j, vector &m, int n, string ds) { if(i < 0 || j < 0 || i >= n || j >= n || m[i][j] == 0) { // if we are beyond boundary / current is blocked = 0 return; } if(i == n-1 && j == n-1) { // If we reached the end ans.push_back(ds); ds = ""; return; } m[i][j] = 0; // set current visited so it wont picked up next time solve(i, j+1, m, n, ds + "R"); solve(i, j-1, m, n, ds + "L"); solve(i+1, j, m, n, ds + "D"); solve(i-1, j, m, n, ds + "U"); m[i][j] = 1; // backtrack it to 1 } vector findPath(vector &m, int n) { string ds = ""; if(m[0][0] == 0 || m[n-1][n-1] == 0) // If we cannot start at first position or end return {}; solve(0, 0, m, n, ds); return ans; } };
@techtsunami6814
@techtsunami6814 2 жыл бұрын
Senior sir aapko comments section mai dekh kar Khushi hui
@navendraagrawal
@navendraagrawal 2 жыл бұрын
@@techtsunami6814 are bhai 🙏🙏 Lage raho bhai striver ki sari video dekh dalo 😂
@kumaranuj03
@kumaranuj03 Жыл бұрын
Thanks @takeUforward for this amazing playlist , Now I am able to think about the approach by my own.
@arkojeetbera8584
@arkojeetbera8584 Жыл бұрын
We can just do the following: grid[i][j] = 0; ; grid[i][j] = 1; //-> backtrackin' step Yeah I know; many will disagree, saying we shouldn’t tamper with the original data, and I too agree with you as I abide by the same principle. But in this case if you see at the end, no cells are tampered, as we are replacing back the original values during the backtracking step. In my opinion, we can overlook the tamper factor as in this way we are not using another nxn auxiliary space (vis). Code: class Solution{ private: vector ans; void run(vector &grid, int n, int i=0, int j=0, string osf=""){ if(i=n || grid[i][j]==0) return; if(i==n-1 && j==n-1){ ans.push_back(osf); return; } grid[i][j] = 0; run(grid, n, i+1, j, osf+"D"); run(grid, n, i, j-1, osf+"L"); run(grid, n, i, j+1, osf+"R"); run(grid, n, i-1, j, osf+"U"); grid[i][j] = 1; //backtrackin' step } public: vector findPath(vector &m, int n) { run(m, n); return ans; } };
@iamnottech8918
@iamnottech8918 5 ай бұрын
I just thought the same and was wondering why he did'nt did that ,now i got it will will tamper the given data and i agree with you at the end it will just do the same and safe space
@ravikant1756
@ravikant1756 Ай бұрын
thanks brother,, i also thought same way .
@ShoyoHinata-ew4vn
@ShoyoHinata-ew4vn 9 күн бұрын
what if grid[i][j] is already 0 your code will change it to one
@bhuvandahal421
@bhuvandahal421 10 ай бұрын
I think this is easier to understand 😘🥰 // Rat in a Maze void mazeSolver(int row, int col, int& n, string& temp, vector& ans, vector& maze) { if(row == n - 1 && col == n - 1) { ans.push_back(temp); return; } maze[row][col] = 2; // Down if(row + 1 < n && maze[row + 1][col] == 1) { mazeSolver(row + 1, col, n, temp + "D", ans, maze); } // Left if(col - 1 >= 0 && maze[row][col - 1] == 1) { mazeSolver(row, col - 1, n, temp + "L", ans, maze); } // Right if(col + 1 < n && maze[row][col + 1] == 1) { mazeSolver(row, col + 1, n, temp + "R", ans, maze); } // Up if(row - 1 >= 0 && maze[row - 1][col] == 1) { mazeSolver(row - 1, col, n, temp + "U", ans, maze); } maze[row][col] = 1; }
@shivamtiwari3672
@shivamtiwari3672 2 жыл бұрын
Thanks striver, your videos are really helpful ,first time I wrote the whole code without seeing the video
@akshitmangotra5370
@akshitmangotra5370 Жыл бұрын
Man I just love you alot. thanks for such beautiful entire series. I loved it so so so so sos much.. Even now I feel confident about Recursion. Earlier to I was like Bro.. what the topic is it. Thanks once again lot for this series.. Love you alot man for your efforts. :)
@nagame859
@nagame859 Жыл бұрын
I watched all the recursive videos in this playlist. And the best thing is I solved this problem myself! Can't thank you more sir🙏🙏..
@chaitanyakumar9229
@chaitanyakumar9229 3 жыл бұрын
vis is not required, you can block the path ( put - 0) in curr posn and call solve fn then make it 1 again (backtracking)
@vaishnavisood9699
@vaishnavisood9699 2 жыл бұрын
Can you explain it..a little more?
@chaitanyakumar9229
@chaitanyakumar9229 2 жыл бұрын
@@vaishnavisood9699 like use backtracking method (recursive way ) everytime you visit a cell, call a function for all the 4 neighbours, but as one of them is the cell that you are on at present, just mark it unreachable by marking it zero and after the 4 recursive calls make it 1 again !
@sujan_kumar_mitra
@sujan_kumar_mitra 2 жыл бұрын
Modifying the input may not be allowed
@chaitanyakumar9229
@chaitanyakumar9229 2 жыл бұрын
@@sujan_kumar_mitra then you might use this, but in gfg and leetcode it was allowed to modify input
@sujan_kumar_mitra
@sujan_kumar_mitra 2 жыл бұрын
@@chaitanyakumar9229 in online platform, it is allowed, but in interview, the interviewer might say that input cannot be modified (read about importance of immutability), so it's better to use separate visited array. But if space constraints are present, then we have to modify the input array
@indroneelgoswami5654
@indroneelgoswami5654 14 күн бұрын
The feeling after solving the question myself by just watching 6 minutes of the video is INSANE!!
@Tomharry910
@Tomharry910 Жыл бұрын
This concludes me watching your recursion + backtracking series videos. It was very informative loaded with great explaination, plus it was fun to watch your videos. Many Many Thanks, Striver!
@shashankarora2945
@shashankarora2945 Жыл бұрын
I used to be afraid of recursion but now it is one of my strong topics and i am so proud of it thanks a lot striver sir
@TheSketchbookSessions.656
@TheSketchbookSessions.656 2 ай бұрын
This " vis[0][0] =1 " should be done before calling the solve function. Otherwise compiler will come at (0,0) index again ,and that cause wrong output. Testcase for the above case is n=2 {{1,1},{1,1}}. In for loop approach.
@sanketwakhare27
@sanketwakhare27 2 жыл бұрын
Thanks Striver for this wonderful video. Really helpful to understand. Keep up the great work!
@anandbabu9219
@anandbabu9219 6 ай бұрын
you are one of my great teachers in my life thank you, you are younger than me you are helping me to under achieve my goals
@indycall1933
@indycall1933 Жыл бұрын
Hi can anyone please explain why we didn't pop the last added char to the string while backtracking. Thanks in advance
@bitbuybit9193
@bitbuybit9193 2 жыл бұрын
After understanding question i paused video and tries to solve it in my own.. and I solved it😍😍😍Pressed liked button..will start dp series from tomorrow
@rajansharma9066
@rajansharma9066 3 ай бұрын
the cordinate is also important to decide where we go like when we go to Down then x=x+1, and y=y, similarly for other parts accordingly.
@loukikraina1783
@loukikraina1783 2 жыл бұрын
We can change the a[i][j] = 0, instead of using extra space for keeping visited blocks marked. Then after recursive call, change a[i][j] to the previous value (Backtracking).
@takeUforward
@takeUforward 2 жыл бұрын
Modifying input is considered as space only
@loukikraina1783
@loukikraina1783 2 жыл бұрын
@@takeUforward Ok Sir, Thank you for making such amazing videos.
@vibhavsharma2724
@vibhavsharma2724 3 ай бұрын
Thank you striver for this great recursion series as now because of you only I can now able to build logic of my own. In this video also after watching the problem in first few minutes, I can able to solve the problem. Thank you...
@kamalsingh1345
@kamalsingh1345 Жыл бұрын
Amazing playlist for recursion, Aag lga di bhaiya 💥💥💥💥💥💥💥💥👌
@percussionistbypassion2931
@percussionistbypassion2931 Жыл бұрын
The ultimate optimization is really outstanding.
@pranavsharma7479
@pranavsharma7479 2 жыл бұрын
bettr is not to use extra space just keep on marking the visited locations on the matrix and while backtracking make it as it was earlier.
@adityan5302
@adityan5302 2 жыл бұрын
python solution : Refer only if you find difficulty in construction the code : class Solution: def findPath(self, arr, n): # code here res = [] vis = [[0 for i in range(n)] for j in range(n)] def solve(i, j, st=""): if i==n-1 and j==n-1: res.append(st) return # Downward if i+1=0 and arr[i][j-1] == 1 and vis[i][j-1] == 0: vis[i][j] = 1 solve(i, j-1, st+"L") vis[i][j] = 0 # Right if j+1=0 and arr[i-1][j] == 1 and vis[i-1][j] == 0: vis[i][j] = 1 solve(i-1, j, st+"U") vis[i][j] = 0 if arr[0][0]: solve(0, 0) return res
@MotivateHours
@MotivateHours Жыл бұрын
Even it can be further optimized in terms of space complexity as we dont need to carry a Visited array just mark the 1of original given array to 0 and again 1 at the time of backtracking
@Ace-ex9gg
@Ace-ex9gg Жыл бұрын
it took me around 40min to solve this thing i guess. Solved it with that optimal approach itself.
@AbhishekKumar-yd7ls
@AbhishekKumar-yd7ls 9 ай бұрын
I solved this without seeing the explanation. This whole series is awesome ❤
@wisdomkhan
@wisdomkhan 2 жыл бұрын
Wow, bhaiya, thanks to you that i did this almost by myself. I was right to keep faith in you and keep watching the videos and type the code. FInally!
@parthsalat
@parthsalat 2 жыл бұрын
Complexity analysis: 16:50
@deVamshi
@deVamshi 2 жыл бұрын
You don't know how grateful i am for your content. Thank you very much!
@sanketh768
@sanketh768 Жыл бұрын
I think some cells will get visited more than once as per the code when we mark it unvisited so that the same cell will be picked by other recursive calls . Even the recursive tree says that the cell (2,1) is a part of 2 of the paths
@dom47
@dom47 Жыл бұрын
when u back track even the visited cell becomes unvisited
@sanketh768
@sanketh768 Жыл бұрын
@@dom47 so the TC cannot be O(Rows * columns) right? Like whenever it's given each cell can be visited only once I tend to calculate it like total no of cells
@tasneemayham974
@tasneemayham974 Жыл бұрын
I have two questions, Striver. Why didn't you remove the last character in the string when backtracking? And the second one is: Why are the directions like that? I mean if you are standing at m[0][0] and you want to go down, it's m[1][0], because you are increasing the rows, and staying at the same column right? It has nothing to do with the real x and y directions? THANK YOU FOR THE AMAZING CONTENT!!!!!!!!!!!!!!!!!
@pratikdas1780
@pratikdas1780 Жыл бұрын
This question is pretty easy to solve if you're familiar with graphs. It's simple DFS+Backtracking. Also, try to solve Word Search alongside this problem, they're pretty similar.
@sakshipathak1855
@sakshipathak1855 Жыл бұрын
what if i use bfs?
@mohitsingh7793
@mohitsingh7793 Жыл бұрын
Time completxity : O(4^(N*N)) Space complexity :O(N*N)(visted-matrix) Auxilliary Space : O(N*N) Correct me I was wrong...
@Aryan-fi2qf
@Aryan-fi2qf 2 жыл бұрын
I think you should put vis[0][0]=1 so that it doesn't travel twice through (0,0). In case of m=[[1,1],[1,1]] we shouldn't accept DURD, RLDR as correct ans right?
@abhisheksuryavanshi979
@abhisheksuryavanshi979 Жыл бұрын
Yes correct, Else we would get wrong answer for testcase 2 1 1 1 1 Changes-> if(m[0][0]==1){ vis[0][0]=true; findPathForRat(i,j,n,temp,m,ans,vis); }
@viraj701
@viraj701 Жыл бұрын
don't forget to add vis[0][0]=1 before you go for recursion
@skilz9525
@skilz9525 Жыл бұрын
got error bcoz of that only XD
@JaspreetChhabra
@JaspreetChhabra 3 жыл бұрын
Best explanation so far !! Amazing. Thanks a lot :)
@jacksparrow1316
@jacksparrow1316 3 жыл бұрын
Its very helpful bro...plz dont stop.it💯♥️
@shreoshighosh5561
@shreoshighosh5561 3 жыл бұрын
please dont stop this series..
@udaytewary3809
@udaytewary3809 Жыл бұрын
Really bhaiya u are goat this the time where I have written the recursion code in go without any error And whole credit goes to you bhaiya ❤️❤️❤️❤️❤️‍🔥❤️‍🔥❤️‍🔥❤️‍🔥
@dipeshdarji6253
@dipeshdarji6253 3 жыл бұрын
Can you please add time and space complexity analysis in your upcoming tutorial? It will be a great help.
@ajaybedre4199
@ajaybedre4199 2 жыл бұрын
Bro don't skip the video in between. He had explained time and space complexity in all the tutorial in this series, actually in this video also at 17.50
@aeroabrar_31
@aeroabrar_31 Жыл бұрын
​@@ajaybedre4199 at 17:50
@vishnum7033
@vishnum7033 Жыл бұрын
sir your explanation is amazing as always , if(i=n || grid[i][j] ==0 || vis[i][j] ) return; if(i==grid.size()-1 and j==grid.size()-1) { ans.push_back(s); return; } vis[i][j] =1; solve(i+1,j,grid,s+"D",ans,vis); solve(i,j-1,grid,s+"L",ans,vis); solve(i,j+1,grid,s+"R",ans,vis); solve(i-1,j,grid,s+"U",ans,vis); vis[i][j] =0;
@PuranKaul
@PuranKaul 2 ай бұрын
why did we not mark the final element in vis at (n-1, n-1).
@arnabchakraborty246
@arnabchakraborty246 2 жыл бұрын
Hatsss off.. Next level of Explanation.Thanks a lot bhaiyaa
@shantipriya370
@shantipriya370 5 ай бұрын
can someone explain why while we are back tracking, the string 'move' is not taken to its previous state?
@DurgaVinayBalla
@DurgaVinayBalla 7 ай бұрын
I think there's no need of extra vis matrix. In my code I've put m[i][j] = 0 (blocked) and then unblocking it instead of vis matrix to know visited or not. it worked out fine. correct me if I'm wrong.
@FaisalKhan-oy4zz
@FaisalKhan-oy4zz 3 жыл бұрын
After truncating the *if part* will it reduce the time complexity? As we are not calling the function 4 times again!? Plz explain me.
@takeUforward
@takeUforward 3 жыл бұрын
No just clean code
@FaisalKhan-oy4zz
@FaisalKhan-oy4zz 3 жыл бұрын
@@takeUforward Ty sir
@stith_pragya
@stith_pragya 4 ай бұрын
Thank You So Much for this wonderful video.................🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻🙏🏻
@roshanraj674
@roshanraj674 3 жыл бұрын
Thank you for explaining it beautifully
@ktsuw_217
@ktsuw_217 3 жыл бұрын
Amazing explanation! Thanks 😊
@ADNANAHMED-eo5xx
@ADNANAHMED-eo5xx 3 жыл бұрын
best tutorial on this topic on youtube
@prateeksomani5803
@prateeksomani5803 2 жыл бұрын
Why don't you have passed string move by reference. I'm getting compilation error if I do that. And also you have not emptied the string s = "" after pushing the string to answer array. Please explain I'm confused here a bit
@vegitogamingpubg3364
@vegitogamingpubg3364 3 жыл бұрын
Time complexity of the efficient solution?
@PADALAVMANOJ
@PADALAVMANOJ 9 ай бұрын
So clean and smooth explanation Anna.
@Tomharry910
@Tomharry910 Жыл бұрын
Fantastic video. Great explaination of code and code logic. Thanks a ton!
@ItsGaganKhatri
@ItsGaganKhatri Жыл бұрын
thankyou Sir, I didnt knew Backtracking Earlier , after watching your video and solving them again myself... I WAS ABLE TO SOLVE THIS ONE WITHOUT ANY HELP #StriverOP
@bhavyajain9969
@bhavyajain9969 Жыл бұрын
vis[0][0] should be assigned value 1 because it's treated as not visited thus, gives redundant and incorrect paths
@Abhishek-yy3xg
@Abhishek-yy3xg 3 жыл бұрын
Bhaiya, can u make an explanation video of Josephus problem.
@tanayshah275
@tanayshah275 3 жыл бұрын
@take U forward, c++ code link is messed up, great explanation btw.
@takeUforward
@takeUforward 3 жыл бұрын
corrected..
@madhusreebera4472
@madhusreebera4472 2 жыл бұрын
can't thank you enough for this course sir!
@talk2city212
@talk2city212 8 ай бұрын
in every loop of if we are approaching towards different position, then we should have mark that as visited. for example in first loop of downward: if(i+1 < n && !visited[i+1][j] && m[i+1][j]==1){ visited[i+1][j] = 1; dfs(m, n, visited, ans, temp+'D', i+1, j); visited[i+1][j] = 0; } if i am doing something wrong, please correct ......
@devisriprasad2021
@devisriprasad2021 6 ай бұрын
i too got the same doubt, did you figure it out?
@talk2city212
@talk2city212 6 ай бұрын
@@devisriprasad2021 Nahi bhai
@sharmaji490
@sharmaji490 3 жыл бұрын
Isn't it a recursion problem Backtracking would be when we need to find if any path exist and if yes then that path as well
@nitinchandrasahu1774
@nitinchandrasahu1774 18 күн бұрын
You can also do this without taking any extra matrix "visited", You can change the given "mat" matrix coordinate to 0 (as blocked), the path that the rat came from. By this, it will never check the path you came from and the TC will be O(3^(N^2)). Code 👇👇 class Solution { public: void solve(int row, int col, string path, vector &ans, vector mat) { int n = mat.size(); if(row==n-1 && col == n-1) { ans.push_back(path); return; } if(row0&&mat[row-1][col] == 1) { mat[row][col] = 0; solve(row-1, col,path + 'U', ans, mat); mat[row][col] = 1; } if(col0&&mat[row][col-1] == 1) { mat[row][col] = 0; solve(row, col-1,path + 'L', ans, mat); mat[row][col] = 1; } } vector findPath(vector &mat) { // Your code goes here vector ans; int n = mat.size(); //Rat can't enter if the entrance is blocked if(mat[0][0] == 1 && mat[n - 1][n - 1] == 1) solve(0, 0, "", ans, mat); return ans; } };
@codeforthought1883
@codeforthought1883 2 жыл бұрын
Bhai 1st half m hi samajh aa jata hai. Hats off
@abhimanyu6534
@abhimanyu6534 3 жыл бұрын
Plz make more videos on concepts that you suggested in the cp video
@jasonbrody4618
@jasonbrody4618 3 жыл бұрын
Instead of visited matrix , can't we use a variable that store from which direction we came from like we came from D-down so we shouldn't check U-up
@jasonbrody4618
@jasonbrody4618 3 жыл бұрын
Like check in string where we came from
@mdfaizanmdfaizan6041
@mdfaizanmdfaizan6041 Ай бұрын
You are a true gem the way you explain❤❤
@ayushjangid273
@ayushjangid273 Жыл бұрын
how the character will be removed from the string 'move' when we backtrack ?
@pleasantdayNwisdom
@pleasantdayNwisdom 3 жыл бұрын
pls tell me ...if without any btech degree ...i can get a job at faang ...i can learn whats needed from internet
@huzefataj7694
@huzefataj7694 2 жыл бұрын
Python code: def solve(i,j,a,n,ans,move,vis): if i==n-1 and j==n-1: ans.append(move) return # Down if i+1=0 and not vis[i][j-1] and a[i][j-1] == 1: vis[i][j]=1 solve(i,j-1,a,n,ans,move+'L',vis) vis[i][j]=0 #right if j+1=0 and not vis[i - 1][j] and a[i - 1][j] == 1: vis[i][j] = 1 solve(i-1,j,a,n,ans,move+'U',vis) vis[i][j]=0 ans=[] n=4 m=[[1, 0, 0, 0],[1, 1, 0, 1],[1, 1, 0, 0],[0, 1, 1, 1]] vis=[[0]*n for i in range(n)] if m[0][0]==1: solve(0,0,m,n,ans,"",vis) print(' '.join(ans)) ********************************************************************************************************* def solve(i,j,a,n,ans,move,vis,di,dj): if i==n-1 and j==n-1: ans.append(move) return dir='DLRU' for ind in range(n): nexti = i + di[ind] nextj = j + dj[ind] if nexti >= 0 and nextj >= 0 and nexti < n and nextj < n and not vis[nexti][nextj] and a[nexti][nextj] == 1: vis[i][j] = 1 solve(nexti, nextj,a,n,ans,move+dir[ind],vis,di,dj) vis[i][j] = 0 ans=[] n=4 m=[[1, 0, 0, 0],[1, 1, 0, 1],[1, 1, 0, 0],[0, 1, 1, 1]] di=[+1,0,0,-1] dj=[0,-1,1,0] vis=[[0]*n for i in range(n)] if m[0][0]==1: solve(0,0,m,n,ans,"",vis,di,dj) print(' '.join(ans))
@iamnottech8918
@iamnottech8918 5 ай бұрын
Before watching the video the idea of solution was very clear in my head thanku for series
@anshumaan1024
@anshumaan1024 Жыл бұрын
GFG pe segmentation fault a rha hai, first approach se class Solution{ // public: void solve(int i, int j, int n, string move, vector &arr, vector &vis, vector &ans){ if(i==n-1 && j==n-1 && arr[i][j]==1 ){ ans.push_back(move); return; } // downward if( i+1=0 && !vis[i][j-1] && arr[i][j-1]==1 ){ vis[i][j] = 1; solve(i,j-1,n,move+'L',arr,vis,ans); vis[i][j] = 0; } // right if( j+1=0 && !vis[i+1][j] && arr[i+1][j]==1){ vis[i][j] = 1; solve(i+1,j,n,move+'U',arr,vis,ans); vis[i][j] = 0; } } public: vector findPath(vector &m, int n) { vector vis(n, vector (n,0)); vector ans; if(m[0][0] = 1) solve(0,0,n,"",m,vis,ans); return ans; } };
@RamanDeep-es6or
@RamanDeep-es6or 3 жыл бұрын
Thank you so much bhaiyaa ♥️💯
@shashankojha3452
@shashankojha3452 3 жыл бұрын
Great Explanation!!!
@sagarmehla2102
@sagarmehla2102 2 жыл бұрын
No need to take the new matrix for storing the visting , unvisting .
@ragul6356
@ragul6356 2 жыл бұрын
Where's the path where you actually run the code , I'm asking you this cuz I've been translating it to python actually and am facing an issue so
@goyal2662
@goyal2662 11 ай бұрын
but where are we emoving the previous direction if it does not go to next part?
@anmolsingh4026
@anmolsingh4026 3 жыл бұрын
Very nicely done bro thanks 😁
@takeUforward
@takeUforward 3 жыл бұрын
Thanks to you
@mayankkashyap1893
@mayankkashyap1893 2 жыл бұрын
Does this code print all the possible path?
@SPonharshitaP
@SPonharshitaP 9 ай бұрын
Please start string series with brute , better and optimal solutions
@bhavyanayyer3391
@bhavyanayyer3391 3 жыл бұрын
Sir pls make video on geek collects the balls which is in greddy algorithm pls sir 🙏🙏
@abhimanyu6534
@abhimanyu6534 3 жыл бұрын
Plz make a video on global and local inversion O(n) soln
@deadindope
@deadindope 2 жыл бұрын
in this visited matrix is not necessary, we can simply do the same things on the matrix also.
@takeUforward
@takeUforward 2 жыл бұрын
In interviews its not a good practice
@sidhantsuman4601
@sidhantsuman4601 3 жыл бұрын
no views but 5 likes and 3 comments wah re you tube
@abhaybanerjee1074
@abhaybanerjee1074 3 жыл бұрын
That is a glitch
@shastriamisha
@shastriamisha 2 жыл бұрын
Great explanation.. Thank you
@lovetocode
@lovetocode 3 жыл бұрын
👍
@vedavyas5953
@vedavyas5953 3 жыл бұрын
can i use dfs and store path string in set and finally sort it n print it
@venkateshn9884
@venkateshn9884 2 жыл бұрын
This is the same approach that striver explained in this video
@gouravkushwaha3001
@gouravkushwaha3001 9 ай бұрын
Very easy problem..striver's explanation makes it more easier
@nikhil_squats
@nikhil_squats 3 жыл бұрын
is development important for faang or mastering dsa is enough?
@codeguy21
@codeguy21 3 жыл бұрын
both are equally important , do on alternative weaks !
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