Counting Sort - O(n) Solution to Sort Colors - Leetcode 75

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[GregHogg]

Master Data Structures & Algorithms For FREE at AlgoMap.io!

[yuuhiiujnj]

I am currently preparing for a Google Phone Interview, and I accidentally scrolled across your video, which is very helpful

[janardannn]

dutch national flag algorithm is the optimal and expected way with N runtime 1 space

[AnAbsolutelyRandomGuy]

You don't need to store the red and just immeduatly add it to array, because it is going to be at the start either way. You could also do same from white, because you know how large the array is

[zrocool]

this is so basic omg, i instantly thought of this upon seeing this

[Pv-vcyu]

Hello Mr.Greg, this ans is a 2 pass solution, but Neetcode explained a one pass answer but it's very complicated.. Mr.Greg if possible just try to explain that version too.. it might improve our way of approaching such problems. (Your ans is GOAT, I just want to learn the other way too)

[СавелийИсаев-ък]

It needs O(n) of additional memory to be sustainable

[technosujeet]

What if interviewer expects me to solve using dnf sort 😂

[wraitth]

can someone provide the full code thats written in the video?

[santhoshm]

Using three pointers we can solve this problem which is the most optimal solution

[vaibhavsharma]

Can someone tell if this approach is correct or not?
I think we can do it with 2 pointers approach. If there are only 3 integers that we have to account for theek we can have a starting index and a last index. So, 0's are supposed to be swapped to the starting index and the 2's are supposed to be swapped with the last index and then increment the starting pointer and decrement the ending pointer. If we just sort 0 and 2, 1 will automatically be sorted.

[yonatannethanel]

If you need to go over the array to count colors, isn’t it O(n)?

[valrina]

So you telling me I only need 32 or 64 extra bits for every single number. Better hope the client doesn't put in a number in the billions 😂

[TheIvasyl]

So it's the same as using HashMap, only with hashmap you get a universal solution any number of different colors

[DCTOR-ZED]

I wouldn't call the space complexity constant simply because the size is known. O(1) implies that it would be the same even if the size changes. If you increase the number of colors, the space required would increase linearly, so O(m) where m is the number of colors.

[jjophoven]

why cant you just move 2s to the end of the list and 0s the beginning

[maixmm]

bro your voice sounds like you're going through puberty