I was amazed that the readership collectively got almost every element of Harry’s solution, except for the monetary payment, and Harry spooking the Dementor instead of destroying it. (Looking up Philip Tetlock’s original experiment on taboo tradeoffs, taking the definition literally instead of reaching, and then reading the relevant section of Ch. 26 while keeping in mind Conservation of Detail, might have solved the monetary part.)
Well, if you make enough guesses, sometimes one of them will be partly right...