LeetCode Word Search Solution Explained

LeetCode Word Search Solution Explained - Java

Рет қаралды 45,428

5 жыл бұрын

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Пікірлер: 37

@luisgualpa7019 3 жыл бұрын

The most relatable programmer lol, thanks for making these videos man

@jingli2168 4 жыл бұрын

It seems that you are not fully understand this problem and just recite the CODE!

@theoDSP Жыл бұрын

My thoughts exactly

@jlecampana 4 жыл бұрын

You fail to explain a very important part of this problem, that is *Why it's not the same as Number of Islands*, and the reason is that you backtrack in line 41: visited[i][j] = false; That part should be carefully explained.

@dmitrykarpenko2271 3 жыл бұрын

Just to have the explanation here: Visited array here marks the currently examinad word so we don't try to use its letter twice (e.g. don't intersect it).

@AvinashS273 3 жыл бұрын

watch this

@vulturebeast 3 жыл бұрын

It's kind of like when we do dfs with that word, we should not consider in the so called dfs graph all the visited words so we mark them as true, but after dfs call gets over.. (all our recursive calls) then we can mark it as false as they're no longer in dfs graph we've needing.

@danrussell_official 4 жыл бұрын

Thanks nick! I just encountered the exact same problem with the “aaa” test case. Unlike you I tried to make a node graph with edges but now that I see your solution i see that I was trying too hard lol. Super helpful thanks man

@Edmundlu 2 жыл бұрын

loving the debugging part at the end!

@yoojinlee9125 Жыл бұрын

Thank you, this is so helpful! I love how you explain the thought process

@yuewu3888 3 жыл бұрын

Thank you Nick, this is very helpful.

@nikhilnaidu1383 3 жыл бұрын

why not index==word.length()-1

@mohanmanu8605 4 жыл бұрын

stuck at exactly same place and then i watched this video

@fairozahmed6888 5 жыл бұрын

Awesome Nick

@JOBFERNANDEZBCD Жыл бұрын

thanks a lot. was stuck at this problem.

@linhnguyenduc641 Жыл бұрын

Thank Nick, I like your idea to create a visited boolean array. Besides, you speed up the algorithm by searching only when the first character in word matches current position in board. ❤

@ProgrammingP123 10 ай бұрын

This was required tho, not an optimization. You can't use the same letter twice

@luciay742 2 жыл бұрын

Thank you so much, it is very helpful!

@charlesbickham6604 4 жыл бұрын

Can someone please explain to me how that if statement that calls recursively works? I understand how it is called but it does not connect how it will return true for me. Thank you.

@ydenda8471 4 жыл бұрын

the main recursive statement calls itself over and over again until a base case is reached for each individual recursive call then returns those values. Basically opening a box with many other boxes inside of it until the last box with the prize is opened.

@shreyrawat7108 11 ай бұрын

hey nick i hope you keep doing what you do.

@azharuddinkhan1865 Жыл бұрын

Very nice solution

@rohit-ld6fc 4 жыл бұрын

Why do we make the visited[i][j] = false again ?

@TinTin-vx4nh 4 жыл бұрын

it's because we need to refresh board and set up visited[I][j] = false in order to check whether other possibilities are true or false.

@mevam123 4 жыл бұрын

This is the most important part of this question. With the help of visited array we are backtracking, we assigned it false because if none of the paths worked out we need to re search the grid starting from afresh.

@audaciouspert1772 2 жыл бұрын

@@mevam123 Thanks for the best explanation out there. Much helpful

@vishwanathpatil2995 4 жыл бұрын

you can just flag the visited element instead of maintaining one more array.

@chrisw4889 4 жыл бұрын

how to flag it

@justanaverageguy4739 4 жыл бұрын

there may be more than one word[0] in board,but we can't pass the same flaged matrix again for another word[0] so there is no way . we need to copy the whole visited matrix again

@pankajrathi 4 жыл бұрын

@@chrisw4889 You can just store it in a temp variable then set the board[i][j] values to empty literal and at the end set back board[i][j] back to temp.

@ravijain8732 3 жыл бұрын

How is this similar to number of islands? The initial for loop is, I suppose, but the algorithm used is completely different. Islands used DFS and this is backtracking

@Sportsandgames6 5 ай бұрын

Technically similar, DFS is based on this type of recursion