Question

This question involves a simulation of a two-player game. In the game, two simulated players each start out with an equal number of coins. In each round, each player chooses to spend either 1, 2, or 3 coins. Coins are then awarded to each player according to the following rules.

Same rule: If both players spend the same number of coins, player 2 gains 1 coin.
Off-by-one rule: If the players do not spend the same number of coins and the positive difference between the number of coins spent by the two players is 1, player 2 is awarded 1 coin.
Off-by-two rule: If the players do not spend the same number of coins and the positive difference between the number of coins spent by the two players is 2, player 1 is awarded 2 coins.

The game ends when the specified number of rounds have been played or when a player’s coin count is less than 3 at the end of a round.

The CoinGame class is shown below. You will write two methods in the CoinGame class.

public class CoinGame

{

private int startingCoins; // starting number of coins

private int maxRounds; // maximum number of rounds played



public CoinGame(int s, int r)

{

startingCoins = s;

maxRounds = r;

}



/** Returns the number of coins (1, 2, or 3) that player 1 will spend.

*/

public int getPlayer1Move()

{

/* implementation not shown. */

}



/** Returns the number of coins (1, 2, or 3) that player 2 will spend, as described in part (a).

*/

public int getPlayer2Move(int round)

{

/* to be implemented in part (a) */

}



/** Plays a simulated game between two players, as described in part (b).

*/

public void playGame()

{

/* to be implemented in part (b) */

}

}

In the simulation, player 2 will always play according to the same strategy. The number of coins player 2 spends is based on what round it is, as described below.

(a) You will write method getPlayer2Move, which returns the number of coins that player 2 will spend in a given round of the game. In the first round of the game, the parameter round has the value 1, in the second round of the game, it has the value 2, and so on. The method returns 1, 2, or 3 based on the following rules.

If round is divisible by 3, then return 3.
If round is not divisible by 3 but is divisible by 2, then return 2.
If round is not divisible by 3 and is not divisible by 2, then return 1.
Complete method getPlayer2Move below by assigning the correct value to result to be returned.

/** Returns the number of coins (1, 2, or 3) that player 2 will spend, as described in part (a).

*/

public int getPlayer2Move(int round)

{

int result;

return result;

}

Write the method playGame, which simulates a game between player 1 and player 2, based on the rules and example shown at the beginning of the question. Both player 1 and player 2 start the game with startingCoins coins. Computer player 1 spends 1, 2, or 3 coins based on the value returned by the method getPlayer1Move(). Computer player 2 spends 1, 2, or 3 coins based on the value returned by the method getPlayer2Move().

The game ends when maxRounds rounds have been played or when a player’s coin count is less than 3 at the end of a round.

At the end of the game, the winner is determined according to the following rules.

If both players have the same number of coins at the end of the game, the method prints "tie game".
If player 1 has more coins than player 2, the method prints "player 1 wins".
If player 2 has more coins than player 1, the method prints "player 2 wins".
(b) Assume that getPlayer2Move works as specified, regardless of what you wrote in part (a) . You must use getPlayer1Move and getPlayer2Move appropriately to receive full credit.

Complete method playGame below.

/** Plays a simulated game between two players, as described in part (b).

*/

public void playGame()

Answer 1

[A] Let's simplify the getPlayer2Move rules first.

• If round is divisible by 3, then return 3

if a number is divisible by another number that means the remainder of the division is 0. We can write the code as follows:

if (round%3 == 0)

result = 3;

• If round is not divisible by 3 but is divisible by 2, then return 2.

Same as the previous one, we are going to use the remainder operation. We can use an else-if condition here.

else if (round%2 == 0)

result = 2;

• If round is not divisible by 3 and is not divisible by 2, then return 1.

An else would work fine here.

else

result = 1;

The full code of part A is attached below.

[B]

playGame method:

Let's have a quick look at the game rules first:

• If both players spend the same number of coins, player 2 gains 1 coin.

This can be translated to if player1Spending == player2Spending, then player2 gets a coin.

• If the players do not spend the same number of coins and the positive difference between the number of coins spent by the two players is 1, player 2 is awarded 1 coin.

If the absolute value of (player1Spending - player2Spending == 1) then player2 gets awarded.

• If the players do not spend the same number of coins and the positive difference between the number of coins spent by the two players is 2, player 1 is awarded 2 coins.

We can either use an else statement or a separate conditional statement here, but I'll go for the else statement.

We can use a while loop to detect when the game ends, either a player's coins is less than 3 OR when the maxRounds have been played.