Can you guys define the problem a little more and improve the test case.

The example provided for n=10 does not actually give the solution to the problem (it shows 21 as the result of the provided guessing pattern); however, if you run a custom testcase the leetcode server say the answer is 16. Can you explain how we arrive at 16. If the number is 8 and we choose 5 7 9, we pay $21. How does one do better than that?

Additionally, the question states: Given a particular n ≥ 1, find out how much money you need to have to guarantee a win. Well, this wording is ambiguous, as I should be able to always return n(n+1)/2 to give the sum of all numbers from 1 to n. That would certainly guarantee a win, right? I think you are looking for the **minimum** amount of money you need to guarantee a win. If so, can you specify that and improve the example to reflect it (and show how the answer 16 is achieved).