Some categories for competitive programming problems

Problem Features

• Arithmetic
• Computational Geometry
• Counting
• Combinatorial
• Distance
• Data Structure
• Enumerating
• Finite State Machine
• (Combinatorial) Game
• Graph
• Hamilton
• implicit/implied
• Manhattan
• Matching
• Number (integer)
• Optimization
• (Un)Ranking
• Rectangle
• Scheduling
• Searching
• Sequence
• Sorting

Solution Features

• Approximation
• Branch & Bound
• Breadth First Search
• Binary Search
• Backtracking
• Divide & Conquer
• Depth First Search
• Dynamic Programming
• Exhaustive Search
• Exponential
• Greedy
• Mathematical Insight
• Meet in the Middle
• Min/Max Spanning Tree
• (Nondet.) Polynomial
• Heuristics
• Hashing
• Linear (Algebra)
• Precomputation
• Recursive
• Shortest Path
• Sweep/Scan Line

via Verhouef • 20 Years of IOI Competition Tasks