Pig Game

Pig is a folk jeopardy dice game with simple rules: Two players race to reach 100 points. Each turn, a player repeatedly rolls a die until either a 1 ("pig") is rolled or the player holds and scores the sum of the rolls (i.e. the turn total). At any time during a player's turn, the player is faced with two decisions:

• roll - If the player rolls a
  • 1: the player scores nothing and it becomes the opponent's turn.
  • 2 - 6: the number is added to the player's turn total and the player's turn continues.
• hold - The turn total is added to the player's score and it becomes the opponent's turn.

Problem:  Implement a game of Pig where the user plays against a "hold at 20 or goal" computer player that rolls until a 1 ("pig") is rolled, or the turn total is greater than or equal to 20, or the score plus the turn total is greater than or equal to 100.  The first player is chosen randomly.

Note: Be sure to "factor out common code".  There is no reason to have two separate, nearly identical sections of code for each player's turn.

Input Format:  An empty input (i.e., Enter) indicates that the user wishes to roll.  Any entered line of non-zero length indicates that the user wishes to hold.

Output Format:

• Before the game, randomly select which player the user will be, and print the line "You will be player #.", where # is the user's player number. Then, print an instruction line "Enter nothing to roll; enter anything to hold."
• Before each turn, print a line with "Player 1 score: " and player 1's score.  Print another line with "Player 2 score: " and player 2's score.  Finally, print a line with "It is player #'s turn.", where "#" is replaced by the current player number.  Play starts with player 1 and then alternates.
• For each roll, print a line with "Roll: " and the random die roll value (1-6).
• For each non-"pig" roll 2-6 on the user's turn, prompt the user with "Turn total: ", the turn total, a tab, and "Roll/Hold? ".
• After a "pig" roll of 1, or a "hold", print a line with "Turn total: " followed by the turn total.  In the case of a "pig", this turn total is 0.  Then, print a line with "New score: " followed by the new score for the current player.

Sample Transcript (input underlined):

You will be player 2.
Enter nothing to roll; enter anything to hold.
Player 1 score: 0
Player 2 score: 0
It is player 1's turn.
Roll: 5
Roll: 3
Roll: 5
Roll: 1
Turn total: 0
New score: 0
Player 1 score: 0
Player 2 score: 0
It is player 2's turn.
Roll: 6
Turn total: 6 	Roll/Hold? (Enter)
Roll: 5
Turn total: 11 	Roll/Hold? (Enter)
Roll: 6
Turn total: 17 	Roll/Hold? (Enter)
Roll: 2
Turn total: 19 	Roll/Hold? (Enter)
Roll: 2
Turn total: 21 	Roll/Hold? h
Turn total: 21
New score: 21
Player 1 score: 0
Player 2 score: 21
It is player 1's turn.
Roll: 5
Roll: 6
Roll: 3
Roll: 5
Roll: 1
Turn total: 0
New score: 0
Player 1 score: 0
Player 2 score: 21
It is player 2's turn.
Roll: 6
Turn total: 6 	Roll/Hold? (Enter)
Roll: 6
Turn total: 12 	Roll/Hold? (Enter)
Roll: 2
Turn total: 14 	Roll/Hold? (Enter)
Roll: 6
Turn total: 20 	Roll/Hold? h
Turn total: 20
New score: 41
Player 1 score: 0
Player 2 score: 41
It is player 1's turn.
Roll: 3
Roll: 3
Roll: 6
Roll: 4
Roll: 4
Turn total: 20
New score: 20
Player 1 score: 20
Player 2 score: 41
It is player 2's turn.
Roll: 3
Turn total: 3 	Roll/Hold? (Enter)
Roll: 3
Turn total: 6 	Roll/Hold? (Enter)
Roll: 2
Turn total: 8 	Roll/Hold? (Enter)
Roll: 2
Turn total: 10 	Roll/Hold? (Enter)
Roll: 4
Turn total: 14 	Roll/Hold? (Enter)
Roll: 2
Turn total: 16 	Roll/Hold? (Enter)
Roll: 4
Turn total: 20 	Roll/Hold? h
Turn total: 20
New score: 61
Player 1 score: 20
Player 2 score: 61
It is player 1's turn.
Roll: 5
Roll: 1
Turn total: 0
New score: 20
Player 1 score: 20
Player 2 score: 61
It is player 2's turn.
Roll: 3
Turn total: 3 	Roll/Hold? (Enter)
Roll: 3
Turn total: 6 	Roll/Hold? (Enter)
Roll: 5
Turn total: 11 	Roll/Hold? (Enter)
Roll: 2
Turn total: 13 	Roll/Hold? (Enter)
Roll: 6
Turn total: 19 	Roll/Hold? h
Turn total: 19
New score: 80
Player 1 score: 20
Player 2 score: 80
It is player 1's turn.
Roll: 3
Roll: 1
Turn total: 0
New score: 20
Player 1 score: 20
Player 2 score: 80
It is player 2's turn.
Roll: 2
Turn total: 2 	Roll/Hold? (Enter)
Roll: 2
Turn total: 4 	Roll/Hold? (Enter)
Roll: 4
Turn total: 8 	Roll/Hold? (Enter)
Roll: 2
Turn total: 10 	Roll/Hold? (Enter)
Roll: 3
Turn total: 13 	Roll/Hold? (Enter)
Roll: 6
Turn total: 19 	Roll/Hold? (Enter)
Roll: 5
Turn total: 24 	Roll/Hold? h
Turn total: 24
New score: 104

Extra Exercises:

1. Use an alternative computer play policy.  Let i be the player's score, j be the opponent's score, and k be the current turn total.  Some alternative play policies:

• Hold at 25 or goal - Hold at the lesser of 25 and 100 - i.
• 4 Scoring Turns - Let t be the number of turns in which a player has held so far.  Hold at floor((100 - i)/(4 - t)).
• Score Base, Keep Pace, and End Race - If i >= 69 or j >= 69, roll for the goal.  Otherwise, hold at the greater of 19 and j - 14.
• Keep Pace and End Race - If i >= 71 or j >= 71, roll for the goal.  Otherwise, hold at 21 + round((j - i) / 8).

2. Allow play of multiple games, alternating the starting player and computing win statistics.

Todd Neller