Add killer-sudoku-helper exercise

[ErikSchierboom]

No description provided.

[tasxatzial]

Just by looking at the description and your solution, i would bump the difficulty to 5 or 6.

Prerequisites: conditionals, vectors or lists (or both), maybe numbers.

Function parameters: All 3 parameters are cage parameters. The general guideline in Clojure is to provide them as a map. So the input would look like {:sum 5 :size 1 :exclude []}. This will also allow practicing map destructuring.

[ErikSchierboom]

Updated!

[tasxatzial]

To keep it simple for future exercises, please disregard what i said here about maps as general guideline. Let's just say we picked maps because it matches the canonical-data and it was a good opportunity for practicing maps. Another good option here would be to use a multi-arity function, with the exclude parameter being optional.

[ErikSchierboom]

Let's keep multi arity functions in mind to find an opportunity to use them!