Problem Categories

Programming Contest problems come in many shapes and sizes. One step that can help in successfully solving a problem is to determine the nature of that problem. One of the easiest ways for people to do this is to make up a list of categories and then decide which category(s) the problem fits into. So here is a first cut in making a list of categories.

Problem Categories

Category	Subcategory	Distinguishing Features
Geometry
	Packing Problems	Fitting some shaped item into another shaped item
	2-D	Can 2-D object X fit in/pass through 2-D object Y
	3-D Perspective	What is visible, are two items the same
	Rotation/Transformation	What happens when a series of rotations/transformations are applied to an object
	Lines	Intersection of lines
	Curves	Circles, Ellipses, Cones, ...
	Triangles	Circumference, area, Right, Isosceles, Equilateral, Scalene, Non-Euclidean
	Quadrilaterals	Square, rectangle, parallelogram, rhombus, trapezoid
	Polygons	Working with many sided figures
Math
	Combinations/Permutations	Solve some puzzle that requires calculation/production of acombination/permutation of items
	Simultaneous Equations	Solve a situation with N unknowns (inequalities also)
	Algebraic	Problems that require use of algebra to solve
	Number Theory	Problems tht require knowledge of number theory to solve
	Trig Relations	Problems tht require trig relationships to solve
	Numerical Relationship	Primes, Pascal's triangle, Fibanacci Series, Factorial
	Trig Relations	Problems that require trig relationships to solve
String
	String Containment	Is some string(s) contained in another string(s)/matrix
	String Manipulation	Heavy string coding: reversing strings, substringing, ...
	Parsing	Problems that rely on parsing input data
Algorithmic
	Sorting/Searching	Problems that need data sorted or searched
	Data Structures	Problems that require understanding of specific data structures tos solve
	Backtracking	Problems that require you to be able to backtrack to solve
	Network	Minimum/maximum distance...
	Graph Problems	Problems that require you to be able to traverse and translate graphs to solve
	Grids	XY grids
	Flood Fill	Filling a bounded region
	Recursive	Recursion -- cool
	Greedy Algorithms	Solve problem by taking best option at each possible step
Other
	Brute Force	Just code away
	Inventory	Classic start with a list, add/remove/modify list, display list of state whether operations are possible
	Dynamic Programming	Can you think sideways...