Casework is a counting approach that breaks a problem into two or more subproblems (the cases) and adding the result from each case together. While casework is sometimes the most elegant method of solution, it may be considered brute force when a more elegant solution exists.
- Casework,Complementary Counting,and OverCounting(PIE) by Sohil Rathi
- AoPS Casework Counting Part 1
- AoPS Casework Counting Part 2