### If there are any blogs that I have missed, please tell in the comment section. Thank you.

# Mathematics Stuff

- Number Theory in Competitive Programming [Tutorial]
- Number of points on Convex hull with lattice points
- FFT, big modulos, precision errors.
- Number of ways between two vertices
- Mathematics For Competitive Programming
- FFT and NTT
- Burnside Lemma
- Number of positive integral solutions of equation 1/x+1/y=1/n!
- On burnside (again)
- Simple but often unknown theorems/lemmas/formula? Do you know?
- Probability of creating a Cycle
- Fast Fourier Transform and variations of it
- Mathematics
- Tutorial on FFT/NTT — The tough made simple. ( Part 2 )
- On continued fractions. Part 2: Properties and interpretation
- [Tutorial] Math note — Dirichlet convolution
- Fast modular multiplication
- Sums and Expected Value — part 2
- Recovering rational number from its remainder modulo huge integer
- Short modular inverse
- The Intuition Behind NIM and Grundy Numbers in Combinatorial Game Theory
- An efficient way to solve some counting problems without matrix multiplication\n
- On Fast Fourier Transform
- [Tutorial] Math note — Möbius inversion
- O(1) runtime prime checking
- [Tutorial] Burnside's lemma (with example)
- [Tutorial] Math note — linear sieve
- [Tutorial] Chinese Remainder Theorem
- A blog on the Sprague-Grundy Theorem
- [Tutorial] Invariants and Monovariants
- Operations on Formal Power Series
- On the mathematics behind rolling hashes and anti-hash tests
- A problem collection of ODE and differential technique
- [Tutorial] Inclusion-Exclusion Principle, Part 1.
- Tutorial on FFT/NTT — The tough made simple. ( Part 1 )
- Sums and Expected Value — part 1
- [Tutorial] Generating Functions in Competitive Programming (Part 2)
- [Tutorial] Generating Functions in Competitive Programming (Part 1)
- [Tutorial] Matroid intersection in simple words
- [Tutorial] Calculate modulo inverses efficiently!
- [TUTORIAL] Basic Lagrange Interpolation
- The Application of Lagrange Interpolation in Mathematics
- [Tutorial] Slight Generalization of Grundy Numbers
- Simple Linear and Effectively Duval Algorithm for Lyndon Factorization
- On the Number of Runs at the Monte-Carlo Method
- [Tutorial] Catalan Numbers and Catalan Convolution
- Counting Divisors of a Number in [tutorial]

# Geometry

- Extremal Triangles
- Preparing for Computational Geometry
- Is the solution of this geometry problem actually optimal?
- Writing a book on geometry, need some feedback
- Two-liners for triangle centers using Barycentric coordinates
- 3D Hull with Coplanar Points
- Quaternion algebra and geometry
- [Tutorial] Slope Trick
- Easy geometry using std::complex
- Geometry: 2D points and lines [Tutorial]
- Original Gym contest: Geometry Special 2018
- O(n) algorithm for finding largest triangle in a convex is wrong?
- How to sweep like a Sir
- Efficient 3D Convex Hull Tutorial
- Writing a book on geometry — Update
- Geometry: Polygon algorithms
- Slope trick explained
- [Tutorial] Slope Trick Visualised
- AlgorithmsThread 7: All Point Pairs
- [Tutorial] Voronoi Diagram and Delaunay Triangulation in O(n log n) with Fortune's Algorithm

# Strings

- Obtaining suffix array from suffix automaton
- String Algorithms
- Suffix tree. Basics. Building in O(nlogn)
- Suffix tree. Ukkonen's algorithm
- Z Algorithm
- On suffix automaton (and tree)
- [C++] basic_string
- Aho-Corasick algorithm. Construction
- A short guide to suffix automata
- Short story about palindromes
- Lexicographically Minimal String Rotation
- Do you really understand Suffix Arrays? An Experiment took a twisted turn!
- Hunt-Szymanski Algorithm Explained (LCS but optimized for special cases)
- [Tutorial] Dictionary of Basic Factors — O(1) String Matching

# Dynamic Programming

- Everything About Dynamic Programming
- Tutorial — "Randomized" DP leading to state elimination
- DP Optimisation Problem
- O(n) solution for 631E (Convex Hull Trick special case)
- DP on Function Calls — Remove a Log Factor
- Fully Persistent Convex Hull Trick
- A range query convex hull problem
- [Tutorial] Recurrent Sequences — Application of combinatorics in DP (basics)
- Hirschberg's Algorithm
- Dp On Trees
- Dynamic Programming on Trees
- [Tutorial] Optimized solution for Knapsack problem
- Digit DP
- [Tutorial]A Complete Guide on Matrix Exponentiation
- "The trick from aliens"
- Introduction to DP with Bitmasking
- Dynamic Programming Optimizations ( Problems )
- AlgorithmsThread Episode 6: Convex Hull Tricks
- Dynamic convex hull implementation
- DP on Trees Tutorial
- [Tutorial] Li Chao Tree Extended
- [Tutorial] Convex Hull Trick — Geometry being useful
- Lecture #3 — Exchange arguments (sorting with dp)
- Matrix Exponentiation tutorial + training contest
- Linear Recurrence and Berlekamp-Massey Algorithm
- Dynamic Programming Optimizations
- [Tutorial] Non-trivial DP Tricks and Techniques
- SOS Dynamic Programming [Tutorial]
- Introduction to Digit Dynamic Programming
- Video Tutorial — Everything about Knapsack Problem
- Convex Hull Trick
- Nice trick involving sparse matrix exponentiation (kind-of)
- An Introduction to Plug DP

# Segment Trees

- Compressed segment trees and merging sets in O(N logU)
- [Video Tutorial] Majority Element Range Queries (Segment Tree)
- Do we actually need lazy propagation on segment trees?
- Persistent segment tree ( Problems )
- Easy and (Semi)Efficient Dynamic Segment Trees (with Policy Hash Tables)
- Segment Tree Beats. A simpler understanding.
- An efficient way to strengthen up your segment tree.
- using merging segment tree to solve problems about sorted list
- Minimum memory consumption by the segment tree
- Segment Tree Problems
- AlgorithmsThread Ep 3: Segment Trees (+ hard ST Problem)
- A simple introduction to "Segment tree beats"
- Efficient and easy segment trees
- Algorithm Gym :: Everything About Segment Trees
- A simple introduction to "Segment tree beats"
- "Efficient and easy segment trees" proof
- Modular Segment Tree with Lazy Propagation
- Sort before insert — A small, yet powerful extension to Merge sort tree
- Segment Tree vs Binary Index Tree (Fenwick Tree): Which is Better?
- Video: Segment Tree Beats
- crazySegmentTree: Segment Tree implementation with 5x faster queries than bottom-up tree

# Mo's Algorithm & Range queries Stuff

- Mo's Algorithm
- Some method for solving RMQ
- Range query data structures
- [Tutorial] 1D and 2D constant time per query range updates (a.k.a difference arrays)
- 2D Range Minimum Query in O(1)
- About performance of sparse tables
- Mo's Algorithm (with update and without update, now you can understand both)
- [Tutorial] Two ways to apply Mo's Algorithm on Trees
- A simple sqrt decomposition solution to online FFT
- SQRT decomposition
- [Tutorial] Square root decomposition and applications
- Fractional cascading is in fact slow?
- [Tutorial] Range minimum query in O(1) with linear time construction
- Everything on Mo's Algorithm
- Algorithms Dead Episode 2: RMQ Tricks!
- On Multidimensional Range Queries
- Mo's Algorithm on Trees [Tutorial]
- [Video Tutorial] Offline Range Queries using Mo's Algorithm
- An alternative sorting order for Mo's algorithm

# Graphs

- Graph Theory Concepts and Problems.
- Faster Dijkstra on Special Graphs [Tutorial]
- Kőnig's Theorem
- Dynamic connectivity problem
- Flow Series
- 2-SAT Tutorial
- Vertex cover and 2-SAT
- 0-1 BFS [Tutorial]
- Are there any learning materials of polynomial minimum cost flow algorithms?
- ICPC Graph Mining Challenge solution
- Algorithm Gym :: Graph Algorithms
- [Tutorial] The DFS tree and its applications: how I found out I really didn't understand bridges
- Story about edge coloring of graph
- Graph Visualizer: Visualize graph inputs
- [Tutorial] 1-K BFS
- Heuristic algorithm for Hamiltonian path in directed graphs
- Shortest Path Modelling Tutorial

# Trees

- A list of important concepts in Tree-based Problems
- Rerooting dynamic Euler tour trees
- [Tutorial] Initializing Binary Indexed Trees in linear time
- [Tutorial] Sack (dsu on tree)
- Non-Recursive HLD Implementation
- [Insight] Number of Topological Orderings of a Directed Tree
- Wavelet Tree Problems
- Understanding Fenwick Trees / Binary Indexed Trees
- Transform Skip list into a BIT with insert operator
- Fenwick tree: initialization in O(N)
- Dominator Tree [Tutorial]
- K-th smallest edge on a tree's path, a tutorial about its approaches
- The Tree Generator — generate different kinds of trees by simple strings!
- On Euler tour trees
- Algorithms Thread 8: Tree Basics (+ Gym Contest)
- Treaps reinvented?
- Sqrt-tree (part 2): modifications in O(sqrtN), lazy propagation
- Finding Bridges Tutorial
- Splay tree tutorial
- Tutorial on Heavy Light Decomposition + Problems
- [Explanation] dsu on trees (small to large)
- Unknown Data Structure — (Sqrt Fragmented Tree)
- Palindromic tree
- [Tutorial] Reachability Tree / DSU-tree
- Nifty implementation of multi-dimensional Binary Indexed Trees using templates.
- Centroid Decomposition on a tree(Beginner)
- Palindromic tree: behind the scenes
- Link-cut tree tutorial
- [Tutorial] Nearest Neighbor Search: Locality-Sensitive Hashing, K-Dimensional Tree, Vantage-Point Tree
- AVL tree without "big rotations"
- Tutorial on Virtual/Auxiliary Trees and YouTube channel
- Link Cut Tree implementation
- Implicit cartesian tree in GNU C++ STL.
- Easiest HLD with subtree queries
- Hybrid Tutorial #-1: Heavy-Light Decomposition
- Sqrt-tree: answering queries in O(1) with O(NloglogN) preprocessing.
- Maintain subtree information using link/cut trees
- Tutorial on Permutation Tree
- [Tutorial] Path sum queries on a tree using a Fenwick tree
- Heavy-light decompositon — it can be simple!
- Heavy-light decomposition implementation
- [Tutorial] Searching Binary Indexed Tree in O(log(N)) using Binary Lifting
- LCA problems
- Online Query Based Rerooting Technique
- Almost-LCA in Tree\n
- DSU with randomized linking is as fast as with rank heuristic
- Introduction to New Data Structure: Wavelet Trees
- [Tutorial] Boruvka's Algorithm
- [Tutorial] a few strange lca algorithms with a few strange time complexities pt 1
- [Tutorial] "1354D — Multiset" + A Gentle Introduction to Fenwick Trees
- A Well-known Data Structure -- Version Tree
- Hybrid Tutorial #-2: Centroid Decomposition

# Z-Category

- A bit more about palindromes
- Tips on Constructive Algorithms
- The most comprehensive Binary Search lecture
- Sublime Text [FastOlympicCoding] — tools for competitive programming
- (almost) Every Algorithms & Data Structures you needed to learn , with practice problems
- Codeforces Visulaizer
- An Introduction to the USA Computing Olympiad -- Book Released
- An Efficient (and quite common) Way to Navigate Grid Problems [C++]
- Ok, lets talk about cout.tie once and forever
- [Tutorial] How to use polygon.codeforces in problem preperation?
- A more elegant solution to 1054H — Epic Convolution
- Bitwise range AND/OR with no updates in O(n) preprocessing and O(1) time per query
- Counting the number of bitmasks in a given array that are submasks of m for every m -- why does this trick work?
- XOR Hashing [TUTORIAL]
- [Tutorial] Easy Introduction to Kitamasa Method
- Finding minimum residue of a linear function in O(log M) time
- About ordered set
- Problem Topics
- [Tutorial] Supporting Queue-like Undoing on DS
- Tricks that I learnt while practicing
- [Tutorial] A powerful representation of integer sets
- Looking for a Challenge 2
- Tips and tricks for solving permutation problems
- [Tutorial] A way to Practice Competitive Programming : From Rating 1000 to 2400+
- Algorithms Thread 9: Treaps (+ Gym Contest!)
- Competitive Programmer's Handbook — a new book on competitive programming
- My opinion on how to practice competitive programming
- TCR trick: Line hashes
- [Tutorial] Generalized Chirp Z-Transform
- How to get started with solving Ad-Hoc tasks on codeforces
- C++ Trick — Easy Debugging / Logging
- C++ STL: Policy based data structures. Part 2
- Random Walk: Hard version
- Venice Technique\n
- What are the greatest programming tips and tricks you have learned on your own by years of coding?
- Add Policy Based Data Structures in the C++ standard
- Game Theory Proof
- The power of assert()
- Matrix
- How does dynamic memory allocation work?
- Derangement Generation of an Array [Tutorial]
- Minimum swaps to sort an array\n
- A Solution of the P versus NP Problem
- Interactive Problems
- Top 5 Optimizations, Tips, and Tricks LGMs Don't Want YOU To Know About !
- Gym Contest with Editorial
- Very useful concepts I haven't seen here
- How to solve problems
- An efficient way to map a permutation (length 11 or 12) to an integer without using std::map
- Binary search on real values
- First Codeforces Tools Website
- Short and important problemsolving advices required
- Improving my Thinking Ability
- A Good Problem
- [Tutorial] Interview preparation guide for Google, Facebook, and other tech companies.
- Tutorial On Tof (Ternary Search)
- Mindf**k of the day — rand() from c++ and Berlekamp–Massey algorithm
- C++ STL: Policy based data structures
- A Bitwise Convolution Tutorial\n
- Useful macro
- Optimal psychological state for programming competitions\n
- A Concise Solution to Problem E from Round #642\n
- Advanced Algorithms and Complexity Course
- Randomization tasks
- The Fear of Gaussian Elimination
- Efficient implementation of Karatsuba multiply with auto-vectorization
- Micro- and macro-management for your next cpp source: General tips'n'tricks
- New data structures
- AlgorithmsThread 5: Persistent Data Structures
- Tutorial on Zeta Transform, Mobius Transform and Subset Sum Convolution
- How do you polar sort?
- Explanation to weird/strange floating point behaviour in C++
- [Tutorial] Kinetic Tournament (Used in FBHC Round 2)
- Fresh and unconventional algorithms & ideas for competitive programming
- Bitwise operations for beginners
- An interesting way of organizing the natural numbers in the tree
- Coding library
- Visualization tool for 2D problems (C++)
- What are the things that you discovered independently?
- An efficient way to control energy in a contest (Part 1+2)
- AlgoWiki: A wiki dedicated to competitive programming
- The history of some recurring problem
- An alternative and very interesting approach on binary search
- Variety of solutions depending on constraints
- Anti-hash test
- Randomized algorithms lecture, part 1 & 2
- Competitive programming course
- All you should know about comparators in C++
- One thing you should know about comparators — Strict Weak Ordering
- How to come up with problem ideas
- MNM Cheating Algorithm
- A simple tool for graph vizualization
- Bitwise operations 2 — popcount & bitsets
- How to get actual 64 bit bitsets on Codeforces [Not Recommended] [Don't do this at your job]
- Bin search and relative error
- Jngen: generic library for generating testcases
- Increase the chance of a random algorithm passing by abusing TLE verdict on Codeforces\n
- ATSP constant approximation: great job, dj3500!
- Blogewoosh #2
- Don't use rand(): a guide to random number generators in C++
- C++ Tricks
- AtCoder Library
- Blogewoosh #1
- How randomized solutions can be hacked, and how to make your solution unhackable
- [Tutorial] Rolling hash and 8 interesting problems [Editorial]\n
- Parallel Binary Search [tutorial]
- Partially Ordered Sets
- [Tutorial] Everything about unordered_map
- C++ STL: Order of magnitude faster hash tables with Policy Based Data Structures
- Minima/maxima over all fixed-size arrays (multi-dimensional)
- Short instruction of formulas writing (translation)
- How to read problem statements
- A problem collection (Spoiler Alert)
- A Beautiful Technique for Some XOR Related Problems
- Blowing up unordered_map, and how to stop getting hacked on it
- How to come up with the solutions: techniques
- Blogewoosh #4
- Blogewoosh #3
- Blogewoosh #5 (with images from now)
- General ideas
- Blogewoosh #7
- N Dimensional Vector (For std::vector Addicts!)
- Cool Code Snippet for Debugging
- Tricks Which Will Increase Your Rating!
- C++ tips and tricks
- Algorithm Gym :: Data structures
- Educational Round 83 problem E (Array Shrinking): O(n log n) solution
- Blogewoosh #6

# CSES Editorial

# Problemsetting

# To Practice Problems

# Have Some Fun

- The Mysterious Nature of Modern Cults on CF — A Documentation
- If Codeforces was an anime
- PART 3 TOP anime characters from CODEFORCES 2021!
- NEW TOP ANIME characters from CODEFORCES 2021!
- TOP ANIME protagonists from CF 2021
- [Clickbait] CF Hot News: ICPC 2021 Secrets
- CF Hot News: Seattle Builds galen_colin orz Statue
- Top 10 optimizations 2017- (collectors edition)

Thanks! It would probably be more helpful to categorize these blogs by topics. I can see some Russian/Hindi blogs, would be nicer to have them listed separately.

Actually, I had these blogs starred, so I didn't do much work here as I just ran a script on my favorite blogs page and then copy-pasted to create this blog (you can see that each blog title is ending with \n). But I will categorize them when I find time.

nice! this is the type of blogs people should post , not, "why indians are have less number of red coders"

thanks mate for this amazing collection.

Thanks! Other similar lists: List 1 List 2

This helped a lot!

Great as it is, those compilations wouldn't be needed if there was working search by tags

I'll bookmark it now and forget it exists after few days, just like any other useful blog.

Matriod intersection barely has any applications in geometry algorithms. It's name might seem to be wierd and delusive, but this topic originates from linear algebra.

DetailsIt is hard to uniquely classify what topic matroid intersection belongs to: it starts in linear algebry, uses set and graph theory and finds appilcations in some other topics. Prerequisites section of the article provides list of topics and approaches that are related to matroid theory and matroid intersection:

Prerequisites.You are not required to know well everything listed here, but it is good to be familiar with some of these concepts for better and faster understanding:I think that it is better to move matroid intersection tutorial from geometry to general mathematical stuff (or probably graphs).

ok

You should add this blog to the list too! lol

LMAO. It would create

"Dark — Codeforces Version".Not possible due to Axiom of regularity!

It is possible, recursion can do it!!!

None of my blogs are on the list

p a i n

Sorry, I searched for all the blogs since 2009 but I never saw your blogs earlier. I will add them first thing in the morning.

While you're at it, can you add Tutorial Voronoi Diagram and Delaunay Triangulation in O(n log n) with Fortune's Algorithm by Monogon?

I just saw the time when these blogs were published. I added a note at the top regarding this. I will soon add all the blogs since September 2020.

Niceeeeeeeeeeeeeeeeeee. This helps me a lot, thanks for your blog!

This blog mentions a funny trick which helped me once in coding a dp task.

You are going to have a special place in heaven pal!

:) And all those who actually wrote these blogs.

I cant believe you didnt include my anime blogs. When compiling a list of most useful codeforces blogs ever, one doesn't simply just leave the anime blogs out. >:(

all jokes aside make a section for most interesting/funny blogs for comic relief since most coders don't laugh that much

Done.

pog jesus 1k upvotes bro you are winning

Thanks, I am very happy that this blog is actually useful to people.

Where is trie :/

No useful blog for trie is published on codeforces.

This one (Already included in the blog) contains intro of Trie.

You forgot to add your own blog :P

is it possible to add blog to favorite or something like that,so i can quickly find it when i need it?

You can add it to favorite by using the star icon next to the upvote/downvote button.

oh thanks,didnt know that

https://mirror.codeforces.com/blog/entry/70018 would fit nicely in your DP section

good job!

Could you add "Problemsetting" section? Including blogs from this, and this...

Also I request to add Top 10 optimizations 2017- (collectors edition) to the Have Some Fun list! Although it covers all the educational blogs you already added.

Done. Nice blogs.

[Tutorial] Dictionary of Basic Factors — O(1) String Matching

Closest Point Pair using sweep-line.

What a useful blog!...

However, I can't read it all

+Have Some Fun

What do you do when your friends do not lock their laptops?

You must add this: https://mirror.codeforces.com/blog/entry/95106 — The Ultimate Topic List : )

U may add Binary Lifting

Great blog,added to favourites. So much things to learn.

Thanks

Cool

salute to you man, but as a noobie i have doubt what is Z category?

Thank you !

I was searching for something like this from many days

broooo.. THANKS

This helps me a lot,thanks friend for this amazing collection.

It was very helpful. Thank you.

Thanks

Thanks for this blog man!

Really Great!

Somebody update this please, this seems really helpful

Great work brother

please update this

Thanks bro