pashka's blog

EDU: Two Pointers Method
By pashka, history, 4 years ago, In English

Hello Codeforces!

It's been a long time since I posted a lesson in EDU section. Sorry about that, was quite busy managing my course on Youtube.

New lesson is about two pointers method.

Go to EDU →

What topics you want to learn next? I would prefer topics not covered in my Youtube course, something more specific for competetive programming. Any ideas?

More about EDU section you can read in this post.

Thanks to Stepavly and Supermagzzz for their help with lecture notes and testing problems.

Enjoy the lesson and good luck on the contests!

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4 years ago, # |
← Rev. 4   Vote: I like it +5 Vote: I do not like it

This is epic!

Suggestions for future topics: Tries, Ternary search, Trees

Also I noticed that this lesson and this lesson are only available in Russian. It would be good if they can be translated into English so more people can learn. Thanks!

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4 years ago, # |
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Ternary Search Please

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    4 years ago, # ^ |
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    Hi! Ternary search is not much important if you know binary search. Ternary search problems can also be solved using binary search. In binary search you will go the mid element and check for the previous and next element and based on your check condition you can either go to left or right.

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      4 years ago, # ^ |
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      You can't do that if the values can be non-integer.

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        4 years ago, # ^ |
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        I am just asking in curiosity. Even if the values are non-integer, and the error allowed in the problem is 'delta' (let which is generally 1e-6). Then can't we check for mid+delta and mid-delta and then eliminate half part according to the check condition.

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          4 years ago, # ^ |
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          You just explained terrnary search, the only difference is that usually in terrnary search the values you mentioned (mid-delta, mid+delta) are selected in a way that they divide the range into 3 equal parts (that's why it's ternary), which makes the code better and less likely to fail because of precision errors.

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4 years ago, # |
  Vote: I like it +3 Vote: I do not like it

Thanks for this. Suggestions : Graphs topics like Trees, DP on Trees, etc.

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4 years ago, # |
  Vote: I like it +31 Vote: I do not like it

FFT please! By the way, i appreciate your work.

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4 years ago, # |
  Vote: I like it +25 Vote: I do not like it

Sqrt Decomposition please

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    4 years ago, # ^ |
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    I am not sure but do we need it when we have segtrees?

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      4 years ago, # ^ |
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      i guess there are some differences on memory usage and time complexity witch makes it better than segtree in some cases.

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      4 years ago, # ^ |
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      Yes, of course. Square root decomposition can handle some types of queries that segment tree can't (or at least it isn't clear that you can handle them).

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4 years ago, # |
  Vote: I like it +13 Vote: I do not like it

My suggestion would be Number Theory and Combinatorics.

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4 years ago, # |
  Vote: I like it +9 Vote: I do not like it

Epic !! Next courses suggestion — Tries

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4 years ago, # |
  Vote: I like it +3 Vote: I do not like it

what about SCC and topological sort, or 2-sat?

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4 years ago, # |
  Vote: I like it +2 Vote: I do not like it

Combinatorics, and NOT dp

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4 years ago, # |
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Combinatorial counting theory please.

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4 years ago, # |
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string

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4 years ago, # |
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Your content is great and very easy to understand! I think more lectures in some hard DP topics (e.g. DP knapsack on Tree, DP on Trie, DP Sum over subsets) or maybe some problems that are a combination of simpler algorithms (like, greedy + DAG, bitmask + shortest paths ...) would be very helpful for a lot of people that know all of the basics, yet struggling to apply them into actual problems.

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4 years ago, # |
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PLEASE DO A COURSE ON COMPUTATIONAL GEOMETRY

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