But we don't need to reverse the one way hash. The goal is simply to find the original password and brute forcing is good enough.
The brute forcing algorithm doesn't care that you only have a partial hash. All that does is increase the chances of collisions. (Side note, rainbow tables might care, I'm not sure how suitable they are for wildcard hash matches)
For example, I burned 8 guesses and I got enough greens to give me 108 bits of the hash. You can scrape out a bit more entropy by processing the yellows and greys, but 108 bits is more than enough to identify the password with very little chance of collisions (the chance of collisions hits only hits 50% once you get to 17 character alphanumeric+symbol passwords).
You can then use the two remaining guesses to resolve any collisions and lock in the correct answer.
