doh, its all obvious in the morning
failing test case
slightly unoptimal solution
more optimal looking version
fix up
soak test shows there are still some bugs
start debugging and instrumenting to find problem
more direct comment
tighten up comments, notice pattern (each guess has the same number repeated at least once)
spelling mistake
refactor: extract variable
no closer to understanding
reads better
continue simplifying until it starts to be understandable