Catalog - Codeforces

→ History

8 days ago User ftiasch inserted blog post Fast convolution for 64-bit integers by quasisphere: inserted field blogEntryId 45298, inserted field catalogFolder FFT and Similar Transformations, inserted field creationTime Dec 1, 2022, 6:39:37 AM, inserted field deleted false, inserted field hidden false, inserted field position 1400.

5 weeks ago User radal inserted blog post A slightly alternative approach for implementation of optimal LCA by monsoon: inserted field blogEntryId 67138, inserted field catalogFolder Data Structures, inserted field creationTime Nov 3, 2022, 2:54:16 PM, inserted field deleted false, inserted field hidden false, inserted field position 1200.

6 weeks ago User Zhtluo updated blog post [Tutorial] Splay Tree: One Tree to Rule Them All by Zhtluo: updated field position 12700.

6 weeks ago User Zhtluo updated blog post [Tutorial] Splay Tree: One Tree to Rule Them All by Zhtluo: updated field catalogFolder ~~Data Structur~~Binary Search Trees.

6 weeks ago User Zhtluo inserted blog post [Tutorial] Splay Tree: One Tree to Rule Them All by Zhtluo: inserted field blogEntryId 108457, inserted field catalogFolder Data Structures, inserted field creationTime Oct 27, 2022, 3:09:38 AM, inserted field deleted false, inserted field hidden false, inserted field position 1200.

6 weeks ago User dario2994 updated blog post Lattice paths and Lindström–Gessel–Viennot lemma by brecurse: updated field englishDescription ~~Description of the Lindström–Gessel–Viennot lemma, which allows to compute a signed sum over disjoint paths in a graph.~~.

6 weeks ago User dario2994 inserted blog post Lattice paths and Lindström–Gessel–Viennot lemma by brecurse: inserted field blogEntryId 108395, inserted field catalogFolder Сombinatorics, inserted field creationTime Oct 26, 2022, 5:23:44 AM, inserted field deleted false, inserted field englishDescription Description of the Lindström–Gessel–Viennot lemma, which allows to compute a signed sum over disjoint paths in a graph., inserted field hidden false, inserted field position 800.

2 months ago User -is-this-fft- inserted blog post Implicit Prime Factorisation by Everule: inserted field blogEntryId 108053, inserted field catalogFolder Number Theory, inserted field creationTime Oct 16, 2022, 7:03:39 AM, inserted field deleted false, inserted field hidden false, inserted field position 1600.

2 months ago User -is-this-fft- inserted blog post Easy online point location algorithm by qwerty787788: inserted field blogEntryId 107901, inserted field catalogFolder Geometry, inserted field creationTime Oct 14, 2022, 4:14:54 AM, inserted field deleted false, inserted field hidden false, inserted field position 2200.

2 months ago User -is-this-fft- inserted blog post Rethink the Dijkstra algorithm -- Let's go deeper by ChristianoPenaldo: inserted field blogEntryId 107810, inserted field catalogFolder Shortest Paths, inserted field creationTime Oct 11, 2022, 7:30:42 AM, inserted field deleted false, inserted field hidden false, inserted field position 400.

2 months ago User peltorator inserted blog post An interesting way to solve 739E by krismaz: inserted field blogEntryId 50036, inserted field catalogFolder Dynamic Programming, inserted field creationTime Sep 24, 2022, 9:42:08 PM, inserted field deleted false, inserted field englishDescription random-shuffle sqrt dp optimization, inserted field hidden false, inserted field position 1100, inserted field russianDescription random-shuffle корневая оптимизация динамики.

3 months ago User -is-this-fft- updated blog post Analysis of polynomial hashing by imachug: updated field position 5400.

3 months ago User -is-this-fft- updated blog post Anti-hash test. by Zlobober: updated field position 4500.

3 months ago User -is-this-fft- updated blog post Analysis of polynomial hashing by imachug: updated field position 6500.

3 months ago User -is-this-fft- updated blog post Kapun's algorithm by imachug: updated field position 5600.

3 months ago User -is-this-fft- updated blog post [Tutorial] Rolling hash and 8 interesting problems [Editorial] by dmkozyrev: updated field position 3200.

3 months ago User -is-this-fft- updated blog post On the mathematics behind rolling hashes and anti-hash tests by dacin21: updated field position 2300.

3 months ago User -is-this-fft- updated blog post [Tutorial] Rolling hash and 8 interesting problems [Editorial] by dmkozyrev: updated field position 4300.

3 months ago User -is-this-fft- updated blog post Anti-hash test. by Zlobober: updated field position 3400.

3 months ago User -is-this-fft- updated blog post [Tutorial] Rolling hash and 8 interesting problems [Editorial] by dmkozyrev: updated field position 5400.

3 months ago User -is-this-fft- updated blog post Kapun's algorithm by imachug: updated field position 4500.

3 months ago User -is-this-fft- updated blog post [Tutorial] Rolling hash and 8 interesting problems [Editorial] by dmkozyrev: updated field position 6500.

3 months ago User -is-this-fft- updated blog post Analysis of polynomial hashing by imachug: updated field position 5600.

3 months ago User -is-this-fft- inserted blog post [Tutorial] Rolling hash and 8 interesting problems [Editorial] by dmkozyrev: inserted field blogEntryId 60445, inserted field catalogFolder Hashing, inserted field creationTime Sep 22, 2022, 2:48:59 AM, inserted field deleted false, inserted field hidden false, inserted field position 600.

3 months ago User -is-this-fft- inserted blog post [Tutorial] XOR Segment Tree by PurpleCrayon: inserted field blogEntryId 105723, inserted field catalogFolder Segment Tree, inserted field creationTime Sep 16, 2022, 5:41:44 PM, inserted field deleted false, inserted field hidden false, inserted field position 1000.

3 months ago User -is-this-fft- inserted blog post [Tutorial] Euler's phi function, its properties, and how to compute it by kamilszymczak1: inserted field blogEntryId 106851, inserted field catalogFolder Number Theory, inserted field creationTime Sep 16, 2022, 5:41:08 PM, inserted field deleted false, inserted field hidden false, inserted field position 1500.

3 months ago User -is-this-fft- inserted blog post Introducing the imaginary cyclic convolution, speeding up convolution by a factor of 2 by pajenegod: inserted field blogEntryId 106983, inserted field catalogFolder FFT and Similar Transformations, inserted field creationTime Sep 16, 2022, 5:37:58 PM, inserted field deleted false, inserted field hidden false, inserted field position 1300.

3 months ago User -is-this-fft- updated folder How to Ask for Help?: updated field englishName How to Aask for Hhelp?.

3 months ago User -is-this-fft- updated folder How to Practice?: updated field englishName How to Ppractice?.

3 months ago User -is-this-fft- updated folder How to Come Up With Solutions?: updated field englishName How to Ccome Uup Wwith Ssolutions?.

3 months ago User -is-this-fft- updated blog post (The Ultimate) Code Library by YouKn0wWho: updated field catalogFolder ~~General~~Libraries.

3 months ago User -is-this-fft- updated blog post AtCoder Library by rng_58: updated field catalogFolder ~~General~~Libraries.

3 months ago User -is-this-fft- updated blog post How to read problem statements by Um_nik: updated field catalogFolder ~~General~~How to come up with solutions?.

3 months ago User -is-this-fft- updated folder General Advice: updated field position ~~100~~-1.

3 months ago User -is-this-fft- updated folder General Advice: updated field position 2100.

3 months ago User -is-this-fft- updated folder Programming Languages: updated field position 1200.

3 months ago User -is-this-fft- updated blog post [Tutorial] The command line: how to read input from file without #ifdef and much more by -is-this-fft-: updated field catalogFolder General Advice.

3 months ago User -is-this-fft- updated blog post Asking for help FAQ by Errichto: updated field catalogFolder ~~General Advice~~How to ask for help?.

3 months ago User -is-this-fft- updated blog post How to ask for help in PM by -is-this-fft-: updated field catalogFolder ~~General Advice~~How to ask for help?.

3 months ago User -is-this-fft- inserted folder How to Ask for Help?: inserted field creationTime Aug 26, 2022, 12:49:21 AM, inserted field deleted false, inserted field englishName How to Ask for Help?, inserted field hidden false, inserted field parentCatalogFolder General Advice, inserted field position 1900.

3 months ago User -is-this-fft- updated blog post [Tutorial] A way to Practice Competitive Programming : From Rating 1000 to 2400+ by E869120: updated field catalogFolder ~~General Adv~~How to practice?.

3 months ago User -is-this-fft- updated blog post How to practice Competitive Programming [Um_nik version] by Um_nik: updated field catalogFolder ~~General Adv~~How to practice?.

3 months ago User -is-this-fft- updated blog post Self-deception: maybe why you're still grey after practicing every day by -is-this-fft-: updated field catalogFolder ~~General Adv~~How to practice?.

3 months ago User -is-this-fft- updated blog post My opinion on how to practice competitive programming by Radewoosh: updated field catalogFolder ~~General Adv~~How to practice?.

3 months ago User -is-this-fft- updated blog post F.A.Q. (in PM) by Um_nik: updated field catalogFolder ~~General Adv~~How to practice?.

3 months ago User -is-this-fft- inserted folder How to Practice?: inserted field creationTime Aug 26, 2022, 12:47:27 AM, inserted field deleted false, inserted field englishName How to Practice?, inserted field hidden false, inserted field parentCatalogFolder General Advice, inserted field position 1800.

3 months ago User -is-this-fft- updated folder Coming up With Solutions: updated field englishName ~~Coming u~~How to Come Up With Solutions?.

3 months ago User -is-this-fft- inserted blog post On "is this greedy or DP", forcing and rubber bands by -is-this-fft-: inserted field blogEntryId 106346, inserted field catalogFolder How to come up with solutions?, inserted field creationTime Aug 26, 2022, 12:46:11 AM, inserted field deleted false, inserted field hidden false, inserted field position 800.

3 months ago User -is-this-fft- updated folder Coming up With Solutions: updated field parentCatalogFolder ~~Algorithms~~General Advice.

3 months ago User -is-this-fft- updated blog post Characteristics of the optimal solution, a technique for finding observations in a problem by Proofy: updated field catalogFolder ~~General~~How to come up with solutions?.

3 months ago User -is-this-fft- updated blog post How to come up with the solutions: techniques by MikeMirzayanov: updated field catalogFolder ~~General~~How to come up with solutions?.

3 months ago User -is-this-fft- inserted folder Coming up With Solutions: inserted field creationTime Aug 26, 2022, 12:44:46 AM, inserted field deleted false, inserted field englishName Coming up With Solutions, inserted field hidden false, inserted field parentCatalogFolder Algorithms, inserted field position 1700.

4 months ago User adamant inserted blog post Duality in linear programming. Part 2 — in competitive programming by adamant: inserted field blogEntryId 105789, inserted field catalogFolder Optimization, inserted field creationTime Aug 9, 2022, 2:23:13 AM, inserted field deleted false, inserted field hidden false, inserted field position 1700.

4 months ago User -is-this-fft- inserted blog post Kőnig's and Hall's theorems through minimum cut in bipartite graphs by adamant: inserted field blogEntryId 105697, inserted field catalogFolder Flows, inserted field creationTime Aug 6, 2022, 10:36:30 PM, inserted field deleted false, inserted field hidden false, inserted field position 900.

4 months ago User -is-this-fft- updated blog post [Tutorial] More about minimum cost flows: potentials and Dinitz by -is-this-fft-: updated field position 8700.

4 months ago User -is-this-fft- updated blog post [Tutorial] Network simplex by brunovsky: updated field position 7800.

4 months ago User -is-this-fft- inserted blog post [Tutorial] More about minimum cost flows: potentials and Dinitz by -is-this-fft-: inserted field blogEntryId 105658, inserted field catalogFolder Flows, inserted field creationTime Aug 5, 2022, 9:04:25 PM, inserted field deleted false, inserted field hidden false, inserted field position 800.

4 months ago User -is-this-fft- updated blog post [Tutorial] Minimum cost (maximum) flow by -is-this-fft-: updated field position 7600.

Catalog

General Advice

How to come up with solutions?
- How to read problem statements – Um_nik – 4 years ago Collection of problems with solutions, with an emphasis on reading the problem statement
- How to come up with the solutions: techniques – MikeMirzayanov – 7 years ago
- Characteristics of the optimal solution, a technique for finding observations in a problem – Proofy – 11 months ago
- On "is this greedy or DP", forcing and rubber bands – -is-this-fft- – 3 months ago
How to practice?
- F.A.Q. (in PM) – Um_nik – 6 years ago
- My opinion on how to practice competitive programming – Radewoosh – 18 months ago
- Self-deception: maybe why you're still grey after practicing every day – -is-this-fft- – 11 months ago
- How to practice Competitive Programming [Um_nik version] – Um_nik – 11 months ago
- [Tutorial] A way to Practice Competitive Programming : From Rating 1000 to 2400+ – E869120 – 4 years ago
How to ask for help?
- How to ask for help in PM – -is-this-fft- – 2 years ago
- Asking for help FAQ – Errichto – 4 years ago
How to use Codeforces [GUIDE] – SlavicG – 10 months ago
[Tutorial] The command line: how to read input from file without #ifdef and much more – -is-this-fft- – 7 months ago
After a Round FAQ – djm03178 – 6 months ago

Algorithms

General General discussions that cannot be attributed to a specific topic
- The Ultimate Topic List (with Resources, Problems and Templates) – YouKn0wWho – 15 months ago
- General ideas – adamant – 6 years ago
- A bit more of general ideas – adamant – 5 months ago
- [Tutorial] Collection of little techniques – -is-this-fft- – 9 months ago
Binary and Ternary Searches
- EDU: Binary Search – pashka – 2 years ago
- [Tutorial] Binary search and other "halving" methods – nor – 13 months ago
- Bin search and relative error – Um_nik – 6 years ago
- Multi-dimensional ternary search – adamant – 11 months ago
- Parallel Binary Search [tutorial] – himanshujaju – 6 years ago
- An alternative and very interesting approach on binary search – Pankin – 3 years ago
Constructive Algorithms
- Tips on Constructive Algorithms – ReaLNero – 2 years ago
Data Structures
- Fenwick Tree BIT
  
  [Tutorial] Searching Binary Indexed Tree in O(log(N)) using Binary Lifting – sdnr1 – 4 years ago
  
  [Tutorial] Path sum queries on a tree using a Fenwick tree – dolphingarlic – 2 years ago
  
  [Tutorial] A Bit of Math, Historic Sum, and Range Add Range Sum Binary Indexed Tree (Fenwick Tree) – FHVirus – 10 months ago
- Segment Tree
  
  EDU: Segment Tree, part 1 – pashka – 2 years ago
  
  Algorithm Gym :: Everything About Segment Trees – PrinceOfPersia – 8 years ago
  
  Efficient and easy segment trees – Al.Cash – 8 years ago
  
  crazySegmentTree: Segment Tree implementation with 5x faster queries than bottom-up tree – imachug – 20 months ago
  
  Compressed segment trees and merging sets in O(N logU) – bicsi – 2 years ago
  
  A simple introduction to "Segment tree beats" – jiry_2 – 5 years ago
  
  Video: Segment Tree Beats – peltorator – 19 months ago
  
  [Tutorial] Li Chao Tree Extended – rama_pang – 23 months ago
  
  using merging segment tree to solve problems about sorted list – TLE – 6 years ago
  
  [Tutorial] XOR Segment Tree – PurpleCrayon – 4 months ago
- Binary Search Trees Cartesian trees, AVL-trees, etc
  
  Algorithms Thread 9: Treaps (+ Gym Contest!) – SecondThread – 2 years ago
  
  Link-cut tree tutorial – ramchandra – 2 years ago
  
  Maintain subtree information using link/cut trees – ouuan – 3 years ago
  
  [Tutorial] Subtree lazy propagation on the link-cut tree – QCFium – 2 years ago
  
  Link Cut Tree implementation – bicsi – 3 years ago
  
  [Tutorial] Splay Tree: One Tree to Rule Them All – Zhtluo – 6 weeks ago
- Disjoint Set Union DSU
  
  EDU: DSU – Aksenov239 – 2 years ago
  
  [Tutorial] Proving the inverse Ackermann complexity of Union-Find – -is-this-fft- – 11 months ago
- Persistence
  
  AlgorithmsThread 5: Persistent Data Structures – SecondThread – 2 years ago
- Algorithm Gym :: Data structures – PrinceOfPersia – 8 years ago
- [Tutorial] Li Chao Tree Extended – rama_pang – 23 months ago
- [Tutorial] Supporting Queue-like Undoing on DS – Noam527 – 2 years ago
- Video about Disjoint Sparse Table or how to answer all queries in constant time – peltorator – 22 months ago
- On Multidimensional Range Queries – Laakeri – 3 years ago Proof (assuming ETH) of the nonexistence of certain data structures
- [Tutorial] A powerful representation of integer sets – brunomont – 2 years ago
- [Tutorial] Kinetic Tournament (Used in FBHC Round 2) – ekzhang – 2 years ago
- Tutorial on Permutation Tree (析合树） – errorgorn – 2 years ago
- Introduction to New Data Structure: Wavelet Trees – rachitiitr – 5 years ago
- [Tutorial] Sparse table – AlexLuchianov – 9 months ago
- Submask range queries – adamant – 6 months ago O(2^{n/2}) for masks of length n
- A slightly alternative approach for implementation of optimal LCA – monsoon – 4 years ago
Divide-and-conquer
- Dynamic connectivity problem – adamant – 8 years ago
- Divide and conquer. Dynamic connectivity offline and DP optimization. Divide and conquer by queries. – Wind_Eagle – 5 months ago
Dynamic Programming DP
- [Tutorial] Non-trivial DP Tricks and Techniques – zscoder – 6 years ago
- Slope trick explained – Kuroni – 3 years ago
- An Introduction to Plug DP – 4fecta – 19 months ago DP on Broken Profile
- Dynamic Programming Optimizations – indy256 – 9 years ago
- SOS Dynamic Programming [Tutorial] – usaxena95 – 7 years ago
- Incredibly beautiful DP optimization from N^3 to N log^2 N – linkret – 6 years ago
- Theoretical grounds of lambda optimization – adamant – 11 months ago Aliens Trick
- [Tutorial] Knapsack, Subset Sum and the (max,+) Convolution – errorgorn – 11 months ago
- [Tutorial]Using Segment Trees to solve Dynamic Programming problems – AlexLuchianov – 9 months ago
- 1D1D-optimization (1D1D-optimization) – seiko.iwasawa – 16 months ago
- An interesting way to solve 739E – krismaz – 6 years ago random-shuffle sqrt dp optimization
Geometry
- [Tutorial] Voronoi Diagram and Delaunay Triangulation in O(n log n) with Fortune's Algorithm – Monogon – 2 years ago
- O(n) algorithm for finding largest triangle in a convex is wrong? – u0qyz1234 – 6 years ago
- Efficient 3D Convex Hull Tutorial – Monogon – 2 years ago
- Dynamic convex hull implementation – dragonslayerintraining – 3 years ago
- Geometry: Polygon algorithms – Al.Cash – 6 years ago
- Half-plane intersection (Blogewoosh #5 (with images from now)) – Radewoosh – 4 years ago
- Quaternion algebra and geometry – adamant – 6 years ago
- Easy geometry using std::complex – Hikari9 – 7 years ago
- Geometry: 2D points and lines [Tutorial] – Al.Cash – 6 years ago
- [Tutorial] Solving Interval Problems with Geometry – Monogon – 11 months ago
- AlgorithmsThread Episode 6: Convex Hull Tricks – SecondThread – 2 years ago
- Visualization tool for 2D problems (C++) – kalinov – 3 years ago
- Some rotational invariants in geometry – adamant – 10 months ago
- Easy online point location algorithm – qwerty787788 – 2 months ago
Games
- A blog on the Sprague-Grundy Theorem – sirknightingfail – 4 years ago
- The Intuition Behind NIM and Grundy Numbers in Combinatorial Game Theory – Shisuko – 4 years ago
- [Tutorial] Slight Generalization of Grundy Numbers – emorgan5289 – 23 months ago Transfinite Grundy numbers
- Nimbers and Sprague-Grundy theorem – adamant – 6 months ago
Graphs
- Depth-first Search DFS
  
  [Tutorial] The DFS tree and its applications: how I found out I really didn't understand bridges – -is-this-fft- – 3 years ago
  
  My own algorithm — offline incremental strongly connected components in O(m*log(m)) – Radewoosh – 18 months ago
- Shortest Paths
  
  0-1 BFS [Tutorial] – himanshujaju – 7 years ago
  
  [Tutorial] k shortest paths and Eppstein's algorithm – meooow – 8 months ago
  
  Rethink the Dijkstra algorithm -- Let's go deeper – ChristianoPenaldo – 2 months ago
- Trees
  
  Algorithms Thread 8: Tree Basics (+ Gym Contest) – SecondThread – 2 years ago Finding diameters, binary lifting and flattening
  
  A list of important concepts in Tree-based Problems – dvdg6566 – 21 month(s) ago
  
  Hybrid Tutorial #-1: Heavy-Light Decomposition – galen_colin – 2 years ago
  
  Heavy-light decompositon — it can be simple! – Vladyslav – 9 years ago
  
  Easiest HLD with subtree queries – adamant – 5 years ago
  
  [Tutorial] Sack (dsu on tree) – Arpa – 7 years ago Small-to-large merging
  
  Hybrid Tutorial #-2: Centroid Decomposition – galen_colin – 2 years ago
  
  Heavy-light decomposition implementation – Al.Cash – 7 years ago
  
  [Tutorial] Path sum queries on a tree using a Fenwick tree – dolphingarlic – 2 years ago
  
  Bridge Trees [Tutorial] – aryan12 – 11 months ago
  
  Line tree (Path max queries on a tree in O(1)) – neal – 3 years ago Description is in Kaban-5 comment
  
  [Tutorial] Binary lifting – AlexLuchianov – 9 months ago
  
  [Tutorial] Tree Isomorphism CSES – Olympia – 9 months ago
  
  [Tutorial] Diameter of a tree and its applications – TheScrasse – 8 months ago
  
  [Tutorial] Fully Dynamic Trees Supporting Path/Subtree Aggregates and Lazy Path/Subtree Updates – smax – 6 months ago
  
  [Tutorial] Theoretically Faster HLD and Centroid Decomposition – errorgorn – 5 months ago
  
  [Insight] Number of Topological Orderings of a Directed Tree – Osama_Alkhodairy – 3 years ago
- Matchings
  
  [Tutorial] Blossom Algorithm for General Matching in O(n^3) – Monogon – 17 months ago
  
  Randomized general matching with Tutte matrix – adamant – 17 months ago
- Flows
  
  [Tutorial, Flows] Project Selection Problem – AlexLuchianov – 8 months ago
  
  [Tutorial] My way of understanding Dinitz's ("Dinic's") algorithm – -is-this-fft- – 5 months ago
  
  [Tutorial] Minimum cost (maximum) flow – -is-this-fft- – 4 months ago
  
  [Tutorial] More about minimum cost flows: potentials and Dinitz – -is-this-fft- – 4 months ago
  
  [Tutorial] Network simplex – brunovsky – 16 months ago
  
  Kőnig's and Hall's theorems through minimum cut in bipartite graphs – adamant – 4 months ago
- Heuristic algorithm for Hamiltonian path in directed graphs – slime – 19 months ago
- [Tutorial] Graph Potentials, Johnson's Algorithm, and Min Cost Max Flow – Monogon – 14 months ago
- Algorithm Gym :: Graph Algorithms – PrinceOfPersia – 8 years ago
- [Tutorial] Boruvka's Algorithm – RockyB – 3 years ago
- Traversing the complement graph in linear/near-linear time in multiple ways – nor – 16 months ago
- Story about edge coloring of graph – ko_osaga – 3 years ago Vizing's Theorem
- Merging Queries Trick – SlavicG – 9 months ago
Greedy Algorithms
- [Tutorial] Matroid intersection in simple words – ATSTNG – 3 years ago
Hashing
- Blowing up unordered_map, and how to stop getting hacked on it – neal – 4 years ago
- [Tutorial] Rolling hash and 8 interesting problems [Editorial] – dmkozyrev – 4 years ago
- On the mathematics behind rolling hashes and anti-hash tests – dacin21 – 4 years ago
- Analysis of polynomial hashing – imachug – 10 months ago
- Anti-hash test. – Zlobober – 10 years ago
- Kapun's algorithm – imachug – 10 months ago
Mathematics
- Bitwise Operations
  
  Bitwise operations for beginners – Errichto – 3 years ago
  
  Bitwise operations 2 — popcount & bitsets – Errichto – 3 years ago
  
  A Beautiful Technique for Some XOR Related Problems – DrSwad – 3 years ago Gaussian elimination, a.k.a xor basis
  
  XOR basis without linear algebra – Everule – 10 months ago
- Number Theory
  
  [Tutorial] Generalized Möbius Inversion on Posets – nor – 11 months ago
  
  [Tutorial] Catalan Numbers and Catalan Convolution – Dardy – 22 months ago
  
  Short modular inverse – _h_ – 7 years ago
  
  Counting Divisors of a Number in $O(N^{\frac{1}{3}})$ [tutorial] – himanshujaju – 7 years ago
  
  Counting primes in $\tilde{{\cal O}}(n^{2/3}\,\,)$ – Maksim1744 – 18 months ago
  
  Finding minimum residue of a linear function in O(log M) time – mango_lassi – 19 months ago
  
  On the Min25 sieve and extensions / SPOJ ASSIEVE – box – 17 months ago
  
  [Tutorial] Math note — Möbius inversion – Nisiyama_Suzune – 5 years ago
  
  [Tutorial] Math note — Dirichlet convolution – Nisiyama_Suzune – 5 years ago
  
  Essential Elementary Number Theory (Essentials of Elementary Number Theory) – Everule – 12 months ago GCD, Bezout's Theorem, Extended CRT, Mobius and other multiplicative functions, Primitive roots and Probabilistic prime tests
  
  A slightly faster algorithm for finding square root modulo an odd prime – hly1204 – 11 months ago
  
  On continued fractions. Part 3: In competitive programming – adamant – 8 months ago
  
  p-adic exponent or why there is a primitive root modulo powers of prime numbers (except 2) – adamant – 7 months ago
  
  [Tutorial] Berlakamp's Algorithm for Polynomial Factorization in a Field (1698G buffed) – errorgorn – 5 months ago
  
  [Tutorial] Euler's phi function, its properties, and how to compute it – kamilszymczak1 – 3 months ago
  
  Implicit Prime Factorisation – Everule – 2 months ago
- Сombinatorics
  
  [Tutorial] Inclusion-Exclusion Principle – Roundgod – 4 years ago
  
  Young Tableaus and the Hook Length Formula – mango_lassi – 12 months ago
  
  [Tutorial] Burnside's lemma (with example) – TwoFx – 4 years ago
  
  [Tutorial] Invariants and Monovariants – TooNewbie – 5 years ago
  
  Catalan Numbers and Generating Uniform Balanced Bracket Sequences – errorgorn – 6 months ago
  
  An intuition and simpler proof for Kirchoff's tree theorem – Everule – 6 months ago
  
  Lattice paths and Lindström–Gessel–Viennot lemma – brecurse – 6 weeks ago
- Probability Theory
  
  Sums and Expected Value — part 1 – Errichto – 4 years ago
  
  Sums and Expected Value — part 2 – Errichto – 4 years ago
  
  [Tutorial] Expected number of coin flips required to achieve a given string – gabrielwu – 11 months ago
- Linear Algebra
  
  A Beautiful Technique for Some XOR Related Problems – DrSwad – 3 years ago Gaussian elimination
  
  Linear Basis (Xor Basis Extended) – errorgorn – 11 months ago Generalization of Gaussian elimination to integers modulo a composite number (and beyond).
  
  2 Special cases of Gaussian [Tutorial] – MazzForces – 4 years ago Markov Chains (for Cyclic Expected Values) and the "XOR basis" technique
- Polynomials, Series and Recurrences
  
  Generating Functions General theory; algorithms are under FFT
  
  [Tutorial] Generating Functions in Competitive Programming (Part 1) – zscoder – 3 years ago
  
  [Tutorial] Generating Functions in Competitive Programming (Part 2) – zscoder – 3 years ago
  
  A problem collection of ODE and differential technique – MiracleFaFa – 3 years ago
  
  Prefix Sum Polynomial – Lain – 11 months ago
  
  Combinatorial species: An intuition behind generating functions – adamant – 6 months ago Simple way to construct generating functions and interpret operations on them.
  
  Moment-generating functions, inversions and q-analogs – adamant – 10 months ago
  
  OGFs, EGFs, differentiation and Taylor shifts – adamant – 10 months ago
  
  Fast polynomial composition – adamant – 8 months ago Given A(x) and B(x), compute first n coefficients of A(B(x)).
  
  Lagrange inversion theorem – adamant – 6 months ago Given x = f(y), find coefficients of g(x) such that y = g(x).
  
  Partitions and pentagonal number theorem – adamant – 5 months ago Explicit formula for (1-x)(1-x^2)(1-x^3)... and applications
  
  FFT and Similar Transformations Algorithms for operating on polynomials
  
  Tutorial on FFT/NTT — The tough made simple. ( Part 1 ) – sidhant – 7 years ago
  
  Notes on FFT / NTT, and the "ultimate" NTT with modulus > 9 * 10^18 – Spheniscine – 3 years ago
  
  On Fast Fourier Transform – adamant – 5 years ago
  
  Operations on Formal Power Series – rng_58 – 5 years ago
  
  Operations on polynomials (on cp-algorithms) – adamant – 4 years ago Fast polynomial division, evaluation, interpolation.
  
  [Tutorial] Generalized Chirp Z-Transform – box – 2 years ago
  
  Discrete Fourier Transform eigenvalues – adamant – 18 months ago
  
  A simple way to understand the transposed algo of multi-eval (A simple way to understand the transposed algo of multi-eval) – hly1204 – 9 months ago
  
  An unexpected D&C with FFT – Um_nik – 6 months ago
  
  Introducing the imaginary cyclic convolution, speeding up convolution by a factor of 2 – pajenegod – 3 months ago
  
  Fast convolution for 64-bit integers – quasisphere – 7 years ago
  
  Bitwise Convolutions Xor-, or- and subset convolution, "set power series"
  
  Generalized FWHT: How I realized I did not understand FWHT – errorgorn – 14 months ago
  
  Tutorial on Zeta Transform, Mobius Transform and Subset Sum Convolution – sidhant – 3 years ago
  
  Fast Walsh Hadamard Transforms and it's inner workings – upobir – 3 years ago
  
  Subset convolution interpretation – adamant – 18 months ago
  
  Optimal Algorithm on Polynomial Composite Set Power Series – Elegia – 17 months ago
  
  Linear Recurrences
  
  Matrix Exponentiation tutorial + training contest – Errichto – 2 years ago
  
  On linear recurrences and the math behind them – adamant – 10 months ago
  
  Recovering a linear recurrence with the extended Euclidean algorithm – adamant – 8 months ago
  
  Half-GCD algorithm – adamant – 8 months ago Compute polynomial GCD or recover minimum recurrence in O(n log^2 n)
  
  Linear Recurrence and Berlekamp-Massey Algorithm – TLE – 4 years ago
  
  [Tutorial] Berlekamp-Massey – smax – 14 months ago
  
  [Math note] On the relationship between gf and me – -is-this-fft- – 17 months ago Correspondence between generating function and matrix exponentiation for solving linear recurrences
  
  [Tutorial] Solving Linear Recurrences with various methods, Including O(N logN logK) using FFT – demoralizer – 12 months ago Computing f(k) where f(k) is a linear recurrence of N terms in O(N * log(N) * log(k))
  
  Hadamard product and binomial convolution of linear recurrences – adamant – 7 months ago
  
  Lagrange interpolation and partial fraction decomposition – adamant – 11 months ago
- Optimization Anything related to mathematical optimization
  
  Multi-dimensional ternary search – adamant – 11 months ago
  
  Theoretical grounds of lambda optimization – adamant – 11 months ago Aliens Trick
  
  Duality in linear programming. Part 1 — definition and construction – adamant – 5 months ago
  
  Duality in linear programming. Part 2 — in competitive programming – adamant – 4 months ago
- [Tutorial] 2-SAT – arujbansal – 17 months ago
- 2-SAT Tutorial – HosseinYousefi – 8 years ago
- Associativity and general identity testing – adamant – 18 months ago
- An interesting algebraic construction – box – 17 months ago
Non-exact and Randomized Algorithms
- [Tutorial] Simulated Annealing in Competitive Programming – PurpleCrayon – 15 months ago
- Randomized algorithms lecture, part 1 & 2 – Errichto – 3 years ago
- Blogewoosh #1 – Radewoosh – 4 years ago
- Blogewoosh #6 – Radewoosh – 4 years ago
- On the Number of Runs at the Monte-Carlo Method – rotavirus – 2 years ago
- Randomized general matching with Tutte matrix – adamant – 17 months ago
- How randomized solutions can be hacked, and how to make your solution unhackable – neal – 4 years ago
Sortings
- Lecture #3 — Exchange arguments (sorting with dp) – Errichto – 4 years ago
Square Root Techniques SQRT decomposition, Mo's algorithm, etc
- [Tutorial] Square Root Techniques – Errichto – 13 months ago
- An alternative sorting order for Mo's algorithm – gepardo – 4 years ago
- Mo's Algorithm on Trees [Tutorial] – animeshf – 7 years ago
- Sqrt-tree: answering queries in O(1) with O(NloglogN) preprocessing. – gepardo – 5 years ago
- [Tutorial] Square root decomposition and applications – box – 2 years ago
- Unknown Data Structure — (Sqrt Fragmented Tree) – cjtoribio – 6 years ago
- [Tutorial] Subset Sum Square Root Optimisation – arujbansal – 12 months ago
Strings
- [Tutorial] Dynamic Suffix Arrays – brunomont – 17 months ago
- On suffix automaton (and tree) – adamant – 7 years ago
- Aho-Corasick algorithm. Construction – adamant – 8 years ago
- A short guide to suffix automata – quasisphere – 7 years ago
- Palindromic tree: behind the scenes – adamant – 8 years ago
- A bit more about palindromes – adamant – 7 years ago You're given a string, split it into the minimum number of palindromes.
- The history of some recurring problem – adamant – 4 years ago You're given a string s and queries: how many distinct substrings does sl...sr have?
- Suffix tree. Ukkonen's algorithm – adamant – 8 years ago
- [Tutorial] Expected number of coin flips required to achieve a given string – gabrielwu – 11 months ago
- [Tutorial] Dictionary of Basic Factors — O(1) String Matching – Leonardo16 – 18 months ago
- Z Algorithm – paladin8 – 11 years ago
Sweeping Line
- How to sweep like a Sir – DanAlex – 7 years ago
- [Tutorial] Finding inclusion hierarchy among circles — An implementation of a sweep-line algorithm – Arpa – 11 months ago
Two Pointers
- EDU: Two Pointers Method – pashka – 22 months ago

Programming Languages

C++
- C++ Tricks – HosseinYousefi – 8 years ago
- Catching silly mistakes with GCC – andreyv – 8 years ago
- Don't use rand(): a guide to random number generators in C++ – neal – 4 years ago
- [Tutorial] GCC Optimization Pragmas – nor – 13 months ago
- C++ tips and tricks – Golovanov399 – 3 years ago
- Performance tip : using std::deque as a memory cache – mouse_wireless – 4 years ago
- C++ STL: Policy based data structures – adamant – 9 years ago Like std::set, but with O(log n) methods to get k-th element and count elements that are less the given one.
- Implicit cartesian tree in GNU C++ STL. – Perlik – 9 years ago Like std::string, but can move substrings around in O(log n).
- A way to use C++ iostream for large input (gcc only) – yak_ex – 12 years ago
- Tutorial on SIMD vectorisation to speed up brute force – maomao90 – 11 months ago
- Generic data structure templates via C++ mixins – clam – 18 months ago
- Explanation to weird/strange floating point behaviour in C++ – pajenegod – 3 years ago Why you sometimes get WA with 64-bit but not 32-bit compiler
- How NOT to use macros – AlexLuchianov – 9 months ago
D
- The D programming language in competitive programming – Gassa – 4 years ago

Meta Posts that are important for competitive programming as a whole

Tools
- CF-Predictor — Know your rating changes! – WasylF – 6 years ago
- Multiple rating graph with other accounts – yak_ex – 12 years ago
- Have you already seen the history of ratings on clist? – aropan – 3 years ago Rating aggregation from different competitive programming sites.
- Codeforces Extensions – MohamedAboOkail – 2 years ago
- Gym Finder – NightRage – 11 months ago
- Userscript: table view in Catalog – -is-this-fft- – 8 months ago
Libraries
- AtCoder Library – rng_58 – 2 years ago A professionally-developed competitive programming library.
- New online judge: Library-Checker! – yosupo – 3 years ago
- (The Ultimate) Code Library – YouKn0wWho – 15 months ago
Announcements Resources that help keeping track of upcoming contests.
- pe in 30 – Golovanov399 – 11 months ago Telegram channel with 30-minutes announcements for new problems at projecteuler.
- OpenCup News – Um_nik – 3 years ago Telegram channel for OpenCup announcements
- Resource clist.x10.mx moved to clist.by – aropan – 11 years ago Contest calendar and more

Problem and Contest Preparation

Testing and Polygon
- Briefly about testlib.h – MikeMirzayanov – 8 years ago
- Generators with testlib.h – MikeMirzayanov – 8 years ago
- Validators with testlib.h – I_love_Hoang_Yen – 8 years ago
- Checkers with testlib.h – Zlobober – 8 years ago
- Interactors with testlib.h – PrinceOfPersia – 7 years ago
- 10 Reasons to Prepare Problems in Polygon – MikeMirzayanov – 8 years ago
- [Tutorial] Polygon.Codeforces Tutorial - A Guide to Problem Preparation [Part 1] – darkkcyan – 9 months ago
- Polygon Updates (Fall-Winter 2014) – Avalanche – 8 years ago
- Testlib and Polygon Updates (June, 2015) – fcspartakm – 7 years ago
- Testlib and Polygon Updates [July, 2018] – MikeMirzayanov – 4 years ago
- Polygon updates (June-October 2019) – geranazavr555 – 3 years ago
- Polygon Updates (June — August 2021) – unreal.eugene – 16 months ago
- Testlib: Opts — parsing command line options – MikeMirzayanov – 3 years ago
- Testlib: tests + CI – MikeMirzayanov – 4 months ago
Problemsetting Interviews with problemsetters, how to come up with problem ideas etc.
- How to come up with problem ideas – Lewin – 4 years ago
- On problemsetting – antontrygubO_o – 3 years ago
- On problemsetting 2 – antontrygubO_o – 3 years ago
- Way of problemsetter – Sammarize – 8 years ago
- What is it like to be a problem writer? – Nickolas – 11 years ago
- Problemsetter's Memoir – Nickolas – 8 years ago
- About Problemsetting (for AtCoder and Codeforces) – dario2994 – 2 years ago

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