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Explore the Group C Olympiad and Autumn Tournament archive.
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274 tasks: 213 from the Municipal, Regional, and National Olympiad rounds (2009–2026), 57 Autumn Tournament tasks (2007–2025), and 4 previously featured problems. 207 tasks have independently written English summaries, analyses, and C++17 solutions; the remaining entries link to Arena. Difficulty labels are learning estimates, not official ratings. Special formats and source clarifications are explained on affected tasks.

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Round / tournamentYearContent

Graphs42

BFS & shortest paths 8

BFS on states 1

BFS with state masks 1

Connected Components 1

Cycle detection 1

Cycle Equations 1

DFS & reachability 5

Dijkstra & weighted routes 7

Directed Bfs 1

DSU & connectivity 2

Graph connected components 1

Grid Distance 1

Lowest common ancestor 1

Minimum spanning trees 1

Multi Source Bfs 1

Permutation cycles & weighted swaps 1

Spanning trees 1

Strongly Connected Components 1

Topological Order 1

Tree path compression 1

Trees & DAGs 3

Trees and DFS preorder 1

Dynamic Programming52

Acyclic State Dp 1

Bitmask Dp 1

Combinatorial Dp 2

Combinatorial DP 1

Counting Dp 1

Digit Dp 1

Digit dynamic programming 14

Dynamic programming 1

Dynamic programming on grids 1

Dynamic programming with parity 1

Grid dynamic programming 1

Grid dynamic programming and path reconstruction 1

Grid path dynamic programming 1

Interval Dp 3

Interval dynamic programming 1

Knapsack 1

Layered Dp 1

Linear Dp 3

Multiple Pointer Generation 1

Ordered States 1

Polynomial Dp 1

Prefix dynamic programming 1

Sequence Dp 1

Sliding Window Dp 1

String Segmentation 1

Subsequence Counting 1

Subset Dp 1

Subset Sum 3

Subset-sum dynamic programming 1

Unbounded Knapsack 1

Greedy Algorithms19

Coverage 1

Digit Construction 1

Enumeration And Packing 1

Greedy algorithms 3

Greedy digit construction 1

Greedy interval matching 1

Greedy matching and sorted scans 1

Greedy scheduling and order statistics 1

Greedy selection & counting 1

Interval Costs 1

Interval Expansion 1

Monotonic Stack 1

Permutations 1

Prefix maxima and forced greedy choices 1

Sorting And Binary Search 1

Sorting Greedy 1

Arrays & Sorting29

Bitwise endpoint preprocessing 1

Boyer–Moore majority vote 1

Bucket arrays and counters 1

Constructive permutation sorting 1

Difference-array invariants 1

Distance Transform 1

Frequency Counting 1

Grid enumeration 1

Interval Merging 2

Matrices & grids 1

Matrix Traversal 2

Prefix Sums 2

Prefix sums and remainders 1

Reverse Difference Arrays 1

Run Length Counting 1

Sorting 1

Sorting and two pointers 7

Sorting with tie breakers 1

Sweep Line 2

Search & Enumeration21

Backtracking 2

Binary search 1

Binary Search 1

Binary search and floor sums 1

Binary search and greedy reductions 2

Binary search and interval covering 1

Binary Search Answer 2

Binary Search On Answer 1

Binary search on the answer 1

Binary search on the answer 2

Digit multiset enumeration 1

Enumeration 3

Sorting and prefix minima 1

Subsequence enumeration and next positions 1

Subset enumeration and calendars 1

Strings14

Coordinate Compression 1

Counting and palindrome construction 1

Hashing 1

Implicit Strings 1

Overlap 1

Palindromes 1

Prefix Function 1

Prefix Sums 1

Run-length encoding 1

Run-length simulation 1

String rotations and big integers 1

Strings 1

Subsequence matching 1

Subsequence recognition 1

Mathematics45

Big integer arithmetic 1

Big integers 1

Big Integers 2

Binary Representation 1

Binomial Coefficients 1

Bitwise Xor 1

Combinatorial block counting 1

Combinatorial counting 1

Combinatorial unranking 1

Combinatorics 3

Compressed Gcd States 1

Digit arithmetic 1

Digit Counting 2

Divisibility 1

Divisor sieves and binary search 1

Divisors 3

Extended Euclid 1

Fractions 1

Gcd And Divisors 1

GCD and relative angular speed 1

Information bounds & binary codes 1

Integer Powers 1

Invariants 1

Mathematics 2

Modular Arithmetic 1

Modular exponentiation 1

Number theory 1

Numeral Systems 1

Permutation unranking 1

Prefix Formulas 1

Prime Factorization 1

Prime factors & sliding windows 1

Prime Sieve 3

Rational Arithmetic 1

Recurrences 1

Sum Identities 1

Geometry10

Angles 1

Circular Intervals 1

Coordinate Geometry 1

Geometry and cross products 1

Geometry and sorting 1

Intervals 1

Polygon Clipping 1

Sorting Faces 1

Sweep Line 2

Data Structures11

Monotonic Queue 1

Monotonic stack 2

Offline stack queries 1

Ordered Sets 1

Sets 1

Stacks & expressions 5

Implementation9

Bit manipulation & decoding 1

Calendar simulation 1

Counting 1

Grid Simulation 1

Interpreters & memoization 1

Ranked Choice Simulation 1

Simulation 3

Topic Not Yet Reviewed22

Awaiting topic review 22

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Browse by topic, then algorithm type. Reviewed tasks include an English summary, worked example, analysis, and commented C++17 code. Catalogue entries link to the official problem.

GROUP C ARCHIVEEASY → HARDC++17

Real problems.Your next challenge.

Your next solution starts here.

Your next solution starts here.

Real problems.
Your next challenge.