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Dongle's Difficult Dilemma

According to legend, three galactic terraformers shaped your planet into a paradise. When their work was done, they left the source of their power behind: three golden hexagons, hidden in dungeons full of traps and monsters. If one person were to bring all three together, they could reinvent the world however they saw fit. Can you collect the hexagons before your rival?

That was thousands of years ago. Today, you’ve learned of Gordon: an evil wizard dead set on collecting the hexagons and enslaving the world to his will. So you set off on a quest to get them first, adventuring through fire, ice, and sand. Yet each time you find that someone else got there first. Not Gordon, but a merchant named Dongle.

At the end of the third dungeon, you find a note inviting you to Dongle’s castle. You show up with a wallet bursting with the 99 gems you’ve collected in your travels, arriving just moments before Gordon, your rival, who also has 99 gems. Dongle has not only collected the golden hexagons, but he’s used them to create 5 silver hexagons, just as powerful as their golden counterparts.

Why did Dongle do all this? Because there’s one thing he loves above all else. Auctions! You and the evil wizard will compete to win the hexagons, starting with the 3 golden ones, making 1 bid for each item as it comes up.

The winners of ties will alternate, starting with you. Whoever first collects a trio of either golden or silver hexagons can use their power to recreate the world.

You’ve already bid 24 gems on the first when you realize that your rival has a dastardly advantage: a mirror that lets you see what you’re bidding. He bids 0 and you win the first hexagon outright.

What’s your strategy to win a matching trio of hexagons before your rival?

Rules:

  1. The first person to collect either 3 golden hexagons or any three of the silver hexagons will gain ultimate power.
  2. The hexagons are auctioned individually, starting with the three golden ones and then five silver ones.
  3. As soon as someone completes a set, the game ends.
  4. You won the first golden hexagon.
  5. You have 75 gems left, and your rival has 99.
  6. You each get to make only one bid for each hexagon, and the higher bid wins.
  7. If there is a tie, the winners will alternate, starting with you. So, you’ll get the auctioned hexagon the first time there is a tie, and your rival will get it the second time, you will get it the third time, etc.
  8. Your rival will know what you’re going to bid each time, but you won’t know his bid.
Solution