"Perverse" problems, that place some arbitary handicap on the programming.
- Source must be in uppercase only : CALENDAR
- Not allowing certain datastructures: strings/arrays/... : Odd word problem
- Restricted I/O
- No comparisons, arithmetic, no lists, no re-reading of input : Longest string challenge
- Code golf challenges : Game of Nim
- The task to be solved depends on the source of the program itself : Quine, Narcissist
See also: Category:Excessively difficult task