Weird Algorithm
The archive starts with the opening Introductory Problems so the workflow can scale cleanly to later categories.
basic simulationmath
CSES Problem Set
Source-backed CSES solution archive with original summaries, rendered editorials, pseudocode when it helps, and exact C++ implementations. Official CSES statements are linked on every page instead of being mirrored here.
15 published solutions
11 supported categories
1 categories with published work
May 21, 2026 most recently updated page
Start here
Begin with the introductory batch
The first published batch covers the opening run of Introductory Problems so the archive can grow from a stable base instead of a one-off dump.
Categories
Archive by official CSES category
Each category page lists the published solutions, their tags, levels, original summaries, and direct links back to the official statement.
Introductory Problems 15 solved
01 Short constructive, simulation, and arithmetic tasks that make good first passes for the archive.
- Weird Algorithm
- Missing Number
- Repetitions
- Increasing Array
Sorting and Searching 0 solved
02 Order statistics, greedy scheduling, binary search, and multiset-driven problem solving.
- No published solutions yet.
Dynamic Programming 0 solved
03 Counting, optimization, and state-transition problems where the recurrence matters as much as the code.
- No published solutions yet.
Graph Algorithms 0 solved
04 Traversal, shortest paths, connectivity, DAG reasoning, and graph decomposition techniques.
- No published solutions yet.
Range Queries 0 solved
05 Fenwick trees, segment trees, sparse tables, and offline ideas for interval-heavy tasks.
- No published solutions yet.
Tree Algorithms 0 solved
06 Subtree aggregation, rerooting, LCA, and other tree-specific techniques.
- No published solutions yet.
Mathematics 0 solved
07 Number theory, modular arithmetic, counting formulas, and constructive math.
- No published solutions yet.
String Algorithms 0 solved
08 Pattern matching, automata, rolling hashes, suffix structures, and combinatorics on strings.
- No published solutions yet.
Geometry 0 solved
09 Coordinate geometry, intersections, orientation tests, convex hulls, and sweepline reasoning.
- No published solutions yet.
Advanced Techniques 0 solved
10 Harder combinations of data structures, optimizations, and structural observations.
- No published solutions yet.
Additional Problems 0 solved
11 Mixed follow-on problems that extend beyond the core category ladder.
- No published solutions yet.
Recent additions
Latest CSES solution pages
These pages all keep the editorial TeX and the C++ source file visible, while the statement stays as an external official link.
01
Introductory Problems
02 Weird Algorithm
Generate the Collatz sequence starting from n and print every value until the sequence reaches 1.
Introductory Problems
03 Repetitions
Find the longest contiguous block of equal characters in the given string.
Introductory Problems
04 Permutations
Construct a permutation of 1 through n where neighboring values never differ by exactly 1.
Introductory Problems
05 Two Knights
For every board size from 1 to n, count how many ways two knights can be placed without attacking each other.
Introductory Problems
06 Two Sets
Split 1 through n into two groups with equal sum, or report that such a partition does not exist.
Introductory Problems
Trailing Zeros
Count how many zeros appear at the end of n! without computing the factorial itself.