Image Smoother - Leetcode 661 - Python

0:00 - Read the problem
0:30 - Drawing Explanation
4:35 - Coding Explanation
8:26 - Drawing Explanation Optimal
12:26 - Coding Explanation Optimal

leetcode 661

#neetcode #leetcode #python

[AMakYu]

I solved this problem easily on my own the first way, but I was curious what kind of explanation you had with a 16 min video since I didn't think this problem warranted that amount of time. Glad I clicked cause that second solution is amazing. Even when I can solve these on my own, I get value from these videos. Thanks.

[chugisan]

To get the last 8 bits (at line 14), you can also AND the number with 255. (AND operation is more efficient than mod).

[PegasusKr]

amazing. never thought that 255 constraint can be used to such solution

[theruler]

If someone still has any confusion why we are using %256, Lets forget binary, think about a decimal number 23456. What if we want to get the last digit? we use %10. What if 2 digit? We just use %100 (10*10=10^2), incase of 3 digits %1000 (10*10*10= 10^3) and so on. We get a pattern here. It's like %base^num_of_digits.
In this problem we want to get the number that is represented by the last 8 bit. Now, just think in the decimal number way, if we want to get the last 8 digit what should we do? mod by 10^8 (following the pattern).
Incase of binary, base =2 and number of digits we want =8. So according to the pattern we have to do %2^8 which is equal to %256. So that's it what we are doing. (Hope it's not making the thing more complicated.)

It can be also done by &255 .

[hyperboliq]

the optimal solution was pretty cool! Bit manipulation questions are so satisfying to solve!

[robin_c]

i'm amaze how you can come up with the optimal solution.

[syeedtalha]

What a lucid explanation! Keep this up!

[MP-nyep]

Great explanation as always. Thank you for the daily problems.

[a_maxed_out_handle_of__chars]

this was a good solution, I solved it using the first approach and liked your second approach :)

[EzWorkzzStudios]

Second solution was sooo intuitive man...

[EzWorkzzStudios]

Amazing naive explanation, helped understanding the rest of the video!

[shreehari]

Definitely medium problem and there is no way I would come up with the second solution.

[jayberry]

Why the memory is same before and after optimization on leetcode? I know in theory it should be less but I wonder why it works differently

[GCKteamKrispy]

We learnt it in Digital signal processing. Couldn't understand the programming side of it. Thanks

[il]

Do we need to come up with the inplace solution in an interview?

[jamesabasifreke]

For the second approach, instead of mod 256 would using logical & work? To remove everything besides last 8?

[krzysztofsobocinski]

I just wondering if you could use sums to avoid internal iteration for each element to make the algorithm a bit faster (roughly 9 times faster)

[CS_nb]

I don't get why we need to XOR and can't just add?

[adityaln]

thats not really constant space bro, cmon