CCC 2016 J5/S2 Tandem Bicycle Solution: Sort First, Then Pairing Has Only One Answer
Sort both teams, pair in the same order for the minimum or opposite order for the maximum, and prove why with an exchange argument.
CP Weekly Challenge
CP Weekly Challenge
Weekly competitive programming and CCC practice articles.
CP Weekly Challenge
CCC 2023 S2 Symmetric Mountains Solution: Center Expansion for Minimum Asymmetry at Every Length
Fix each odd or even center, expand outward, and find the minimum asymmetry for every crop length in O(N²).
CP Weekly Challenge
CCC 2022 J4/S2 Group Work Solution: Count Violated Constraints in One Pass with a Dictionary
Map each name to its group with a dictionary, then count every violated constraint in two linear passes, with Python and C++ solutions.
CP Weekly Challenge
USACO 2018 December Bronze Mixing Milk Solution: Simulating 100 Pours
Learn the USACO 2018 December Bronze Mixing Milk solution with direct simulation, cyclic updates, invariants, and tested Python and C++ code.
CP Weekly Challenge
CCC 2023 J4/S1 Trianglane Solution: Perimeter by Counting Shared Edges
Learn CCC 2023 J4/S1 Trianglane with perimeter counting, shared edges, parity, and O(C) Python and C++ solutions.
CP Weekly Challenge
CCC DSA Roadmap: Data Structures and Algorithms from Junior to Senior
A CCC DSA roadmap from Junior to Senior, covering simulation, strings, grids, counting, prefix sums, graph search, greedy, DSU, shortest paths, dynamic programming, and typical historical CCC problems.
CP Weekly Challenge
CCC 2017 S1 Sum Game Solution: Running Prefix Sums and Last Equal Day
Learn how to solve Sum Game with running prefix sums, cumulative totals, and last-valid-position tracking in Python and C++.
CP Weekly Challenge
CCC 2020 J5/S2 Escape Room Solution: BFS on an Implicit Graph
Learn how to solve Escape Room with BFS on an implicit graph, product-to-cells indexing, and visited-value optimization in Python and C++.
CP Weekly Challenge
CCC 2021 J5/S2 Modern Art Solution: Count Gold Cells with Parity
Learn how to solve Modern Art with parity, row and column toggling, and an O(M + N + K) counting formula in Python and C++.
CP Weekly Challenge
CCC 2025 J4 Sunny Days Solution: Longest Sunny Streak After One Fix
Learn how to solve Sunny Days with prefix and suffix streak counts, one-day correction logic, and Python/C++ implementations.