Suppose you have 8 watermelons that are exactly the same in appearance.

They are equal in weight except for one, which is heavier than the others.

You want to find the heaviest one by using a two-pan balance.

Each pan can hold any number of watermelons,

and the only items that you can place in the pans are watermelons.

Find the best strategy to determine the heaviest watermelon.

In the worst case scenario,

How many times do you have to use the two-pan balance ?