Leetcode Visualized: 739. Daily Temperatures

[@jagadish3829]

man where have u been all these times ❣❣❣

[@MortalWombat22]

Still a GOATED video, helping thousands of others 4 years later!

[@iiimiiim]

Amazing! Thank you so much for this😍

[@pi_nheiro7]

Thank you so much, you explain very well!!

[@KushalBhatia]

This world need more people like you. Thank you for all the efforts you took to make this video 🙏👍

[@powerhead]

Thanks for great visualisation! Small optimization. No need to store tuples in the stack, its enough to store only indexes and get values from T by these indexes. And also no need to do additional comparison on line 15 since stack at this point contain only values greater than current day temperature. public int[] warmDays(int[] days) { result = new int[days.length]; Stack stack = new Stack(); for(int day = days.length-1; day >= 0; day--) { while (!stack.isEmpty() && days[stack.peek()]

[@amruthammohan1667]

Just amazing...❣

[@kaitlinzhang1378]

Awesome explanation with great visualizations -- thanks so much for putting this together!

[@viridianite]

Thanks a lot, Alexander! I had seen another similar implementation where you start at the beginning of the array but while I understood the code, I couldn't wrap my head around it and wouldn't have been able to simulate the algorithm with pen and paper. That walkthrough visualization was top notch, keep it up! 15:00 By the way, I think that in this conditional statement you don't need "T[i] < stack[stack.length - 1][0]" given that you already established it with "T[i] >= stack[stack.length - 1][0]" in the while loop. Assuming the stack isn't empty, after all that popping, the day at the stack's top is guaranteed to be warmer than the current day at index i so there's no need to test for it.

[@nikhilmishra7572]

As soon as I saw the stack visual I clicked subscribe button! Great job!

[@BS-eu9do]

Thanks for great visualisation!

[@haifzhan]

Good explanation and I like the way you drag the next pointer!

[@arpansen423]

Thank you, this is the best way to teach algorithms, pl. keep uploading videos regularly

[@zhenlinjin3142]

Thanks a lot for your analysis! The use of array is great because it defaults the empty values to 0, in our case we won't have to manually do for cases when warmer temp is not found.

[@captain_knoxx]

One of the best leetcode explanation videos I have ever seen. Shame you stopped recording them :(

[@rahoolification]

Keep up the good work my friend. Really appreciate it!!!

[@spacesuitred3839]

Amazing explanation and drawing!

[@omarflores4234]

Im speechless! This was a fantastic explanation! As others have pointed out, visualizing these kinds of problems is the key to understanding them. Thank you very much and keep up the good work!

[@xmaxfuture]

Thank you so much Alexander

[@AmanRaj-gy6qv]

Thank you for visualisation, understood the concepts well enough

[@sk45861]

why do we have to walk from last when you can walk the array from the first? e.g for (let i = 0; i < temperatures.length; i++) { while (stack.length && temperatures[stack[stack.length - 1]] < temperatures[i]) { const j = stack.pop()!; result[j] = i - j; // calculate the number of days until a warmer temperature } stack.push(i); // push current index onto the stack for future comparisons } return result;

[@viridianite]

For me, walking the array from the back makes the implementation a lot similar to the way Alexander explained the algorithm, and thus more intuitive to think about it. I.e.: Declare a stack; also declare a result array initialized to 0. Starting from end of the input array, for every temperature at index i: 1. While the stack isn't empty and current temperature at i is warmer (i.e., greater than or equal to) than the temperature at stack's top index, pop the stack. 2. If the stack isn't empty, then we found a warmer day. The number of days till warmer for index i in result array is stack's top index minus current index i. 3. Push current index into the stack. Return result array.

[@SimplyaGameAholic]

you deserve a big blue nice like my friend

[@saladHz]

Welp this example really helped just sucked that it began from the end of the list rather than the beginning

[@maheiramkhan]

Amazing, truly! This visualization helped me so much! I had read so many solutions but couldn't understand. Your visualization made it so easy! Thanks so much.

[@poyanimehta9746]

Great Explanation Looking for more such videos

[@sase1017]

Great job , but Time and Space analysis?

[@shanmukhpatel]

Excellent visual presentation! Thank you!

[@VenkateshReddyMunagala]

Wow! A very with no dislikes and very rightly so. Great Visual demonstration and explanation!

[@Abhinavkmr]

Thank You!

[@snehaashishgupta1254]

Sir, thanking you heartily for making such illustrative videos... please make more such videos on the remaining problems that require more visualization... gosh this channel's so underrated deserves a million views...

[@ahmedouyahya]

very beautiful visualization, and clear explanation. Thank you so much.

[@alexromero3274]

This was perfect! Thank you for your visualized videos. They are a huge help for visual learners!! :-)

[@knowledge_wings]

please make more video ur stuff is wonderful

[@chetanshrivastava3762]

Very nice explanation with visual graphics...

[@neelpawar3340]

This was so good!

[@SiddharthMathur2k007]

Thank You! :)

[@하이-x1i]

Finally I can understand!!! thx!!!

[@DrSeanKennedy-k2b]

Excellent explanation and use of visuals. Where needed I love to use a whiteboard. Subscribed and liked.

[@MrDheeraj14]

Very Well explained :) Really appreciate your efforts! Just a quick change suggestion at line 12: There should not be a equal to, =, check, otherwise it will not pass [89,62,70,58,47,47,46,76,100,70] case. because 47, 47 is repeating element and equal to condition will remove the 47 at 5th index.

[@akshdeeprajawat9642]

Wooooooooooow !

[@kc8478]

very cool

[@manojg4451]

Plzzzzz do more videos ,With this kind of explanation,you will be the to-go channel for leetcode

[@paulomarques8147]

Nice explanation. Subscibed. :+1: Just a note: You could remove the second validation in line 15, as if T[i] was not lower than the elements in the stack, the stack would be empty in that case.

[@kaushiktummalapali4000]

Thanks a ton! Way better explanation than leet code solution break through!

[@keller8064]

Thanks this has been helpful! Also, one thing we can do is instead of pushing the value as well as the index, we can only push the index in an integer array, thus, saving us from making the type array. Here's my C++ code vector dailyTemperatures(vector& T) { vector st; vector ans(T.size(), 0); st.push_back(T.size()-1); for(int i=T.size()-2; i>=0; i--) { while(!st.empty() && T[i] >= T[st.back()]) st.pop_back(); if(!st.empty() && T[i] < T[st.back()]) ans[i] = st.back() - i; st.push_back(i); } return ans; }

[@yeqinghuang2117]

Thank you. The visualization is super helpful.

[@mojo_code]

Fantastic job

[@metin2dare]

ty for sharing

[@peddivarunkumar]

Thanks!

[@yashSharma-pe1dp]

sir please upload visualization of other leetcode problems, coz you teaches very well!!

[@SeadoooRider]

Thanks for the explanation. Great video. Keep doing.

[@samriniqbal5096]

This is so cool.

[@tunabozkurt5578]

Very well done. Thanks.

[@chaitanyapatil6839]

Amazing

[@abdallahelkasass6332]

thank you very very much

[@wesammustafa9004]

Excellent Explanation

[@ash2012ash]

very well explained. Thanks for making me understand this question.

[@Nickel80]

That was a great explanation. Thank you

[@kangniliu7992]

Subscribed!! Awesome explanation!

[@niveenelkhazendar4482]

Really thanks a lot for your explanation, it halp me very much

[@ankitufl]

Great explanation

[@avneetsng]

thanks dude

[@sharmilabaskaran7373]

Thankyou. Please do more leetcode questions

[@MangoDrankE]

Great explanation. Thank you!

[@aliceoioih8471]

Thank you for sharing! I think it'd be better if without the background music

[@Noname-wp6zt]

Great explanation!

[@kingjohnkk]

a very very good explanation and conceptual walkthrough. Didnt have to watch the rest of the video, thats how good the explanation was. Still gonna finish the video - even after having already submitted the answer :)

[@aleyummusic]

What are some other problems similar to this?

[@XXXX-ib1vt]

Is this the Corpse of Leetcode?

[@chankwongyin7455]

best

[@namaratasharma5417]

Hi, Awsm explanation ..would like to know the tool you are using for visualization

[@shivanshsuhane8788]

I couldn't come up with this solution. Is there a particular name to this sort of algorithm (eg: 2-pointer)? If so that's a new concept and I'd like to explore similar questions. If not, that's a definitely creative solution. How did you come up with this? Does it just come with practice? Is it possible to learn this power :O?

[@satyajeetjha1681]

You need to solve problems to be able to solve problems and you need to think hard. It is hard to come up with solutions and it comes with practice. If you do a simple level order traversal of bst, you can easily do right side view of bst as well. So it comes with thinking and time. I assume you aren't God gifted.

[@divyanshdixit4944]

Read about monotonic stacks

[@vinaygupta2369]

O(N) solution is java - public static int[] dailyTemperatures(int[] temperatures) { int length = temperatures.length; int[] output = new int[length]; Stack stack = new Stack(); // use stack for filling the output array for(int i = length-1;i>=0;i--) { while(!stack.isEmpty() && temperatures[i]>=temperatures[stack.peek()]) { stack.pop(); } // If the stack still has elements, then the next warmer temperature exists! if(!stack.isEmpty()) { output[i] = stack.peek() - i; } // Inserting current index in the stack: monotonicity is maintained! stack.push(i); } return output; }

[@kseniaeugene7177]

Why do you need a tuple? you can put only the indices on Stack and then look up the actual value by calling T[stack.peek()]

[@nikunjgupta2107]

Are you God?