The Game of Coins (Solution)

Winning strategy for Player 1:

Remember that before starting the game, players know which chips are on the table and the order in which they are shown.

  • Enumerate the coins’ positions from left to right and see how much the sum of the values on the coins that appear in even positions in the row is and the sum of the values of the coins that appear in odd positions in the row.

  • Choose the greatest value between these two sums. To continue, suppose, without loss of generality, that the greatest sum was that of the coins in even positions.

  • The goal will be to play in such a way that Player 1 will end up with the set of coins in even positions at the end of the game.

  • Notice that when Player 1 makes the first choice, he has as alternatives coin 1 and coin 8 (one in an odd position and the other in an even position). Since the goal is to get the even ones, the choice should be the coinin the even position, and uncovering a new coin, but this time the available coin is in an odd position.

  • On the second round, Player 2 has two possible choices, but both choices are in odd positions. Thus, at the end of his move, there will always be a coin in an odd position, and at this point, he will uncover a coin in an even position.

  • On the third round, we return to the same situation as the first round (Player 1 has two possible choices, one in an even position and the other in an odd position). Since the goal is to end up with all the even ones, the right choice is the coin in the even position.

  • Repeating this process, Player 1 will always have the possibility to choose between coins in even and odd positions, and Player 2 will always be limited to choosing coins in odd positions. Therefore, we can guarantee that in the end, Player 1 will finish the game with the coins in even positions and will be the winner of the match.

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