Description
Introduction
In this assignment, you will use functions to implement a game called Strings and Coins. At the
beginning of the game, there is a network of coins, each connected by four strings. Two players take
turns cutting a string in the network. When a cut leaves a coin with no strings connected, the player
scores one point and takes an extra turn.
Note that the player can get more than two consecutive
turns as long as s/he scores again in every turn.
The game ends when all strings are cut, and the player
with more points wins. It is a draw if two players get the same points. Figure 1 shows an example game
network. We use the symbol $ to denote coins, — and | to denote the strings, and # to denote the
“wall” (that is, the network boundary). In Figure 1(b), the top-left coin is already disconnected
(assumed to be by Player 1), and the bottom-right coin is one string from being disconnected.
##########
# | | #
#–$–$–#
# | | #
#–$–$–#
# | | # Player 1 score: 0
########## Player 2 score: 0
After some
turns
…
##########
# #
# $ $–#
# | #
#–$ $ #
# | # Player 1 score: 1
########## Player 2 score: 0
(a) (b)
Figure 1: (a) Initial network of coins; (b) Network after some turns
Program Specification
This section describesthe game network representation, some necessary functions, and program flow.
Game Network Representation
There are 12 strings initially in the network. Therefore, we use integers 1 to 12 to denote these string
positions, as illustrated in Figure 2. The positions are basically ordered top-to-bottom, left-to-right.
##########
# #
# $ $–#
# | #
#–$ $ $
# | # Player 1 score: 1
########## Player 2 score: 0
Figure 2: Numbers for String Positions
To encode the whole network and the players’ scores in a game, we use a 14-digit integer
𝑑1𝑑2𝑑3𝑑4𝑑5𝑑6𝑑7𝑑8𝑑9𝑑10𝑑11𝑑12𝑑13𝑑14 . The first 12 digits 𝑑1 … 𝑑12 are either 0 or 1, denoting
whether the string in the corresponding positions 1 to 12 are cut or not. (That is, 𝑑𝑖 = 0 means the
string in position 𝑖 is already cut; 𝑑𝑖 = 1 means position 𝑖 remains uncut.) The last two digits 𝑑13 and
1 4 2
12
3
5
6
8
7
10
11
9
𝑑14 range in 0–4 to denote the scores of Players 1 and 2 respectively. For example, the network in
Figure 1(b) is encoded by 00001011001010, which also stores the scores of Player 1 (1) and Player 2
(0). Using this representation, the initial full network (with all strings uncut) is encoded as the integer
11111111111100.
The network at game end (with all strings cut) is encoded as 000000000000xy,
where x and y depend on the scores of Players 1 and 2. For example, 00000000000013 is a game won
by Player 2. (Note: in C++, integer constants should NOT contain leading zeroes, otherwise, they will
be treated as octal numbers.
Therefore, it is actually 13 rather than 00000000000013.)
The data type int in C++ is typically 32-bit and is not big enough to store a 14-digit integer. In your
program, you have to use a bigger integer type called long long. In Visual Studio, long long is a
64-bit signed integer type, whose range is -9,223,372,036,854,775,808 … 9,223,372,036,854,775,807.
Provided and Required Functions
Your program must contain the following functions. Two of them are written for you already (Provided)
and you should not modify their contents. The others will be written by you (Required). These functions
must be called somewhere in your program. You can design extra functions if you find necessary.
(Provided) bool stringStatus(long long network, int pos)
Returns true if position pos of the game network still has a string (not cut yet); returns false
otherwise (that is, string is already cut).
(Provided) void displayNetwork(long long network)
Prints the network to the screen using the format in Figure 1.
(Required) int playerScore(long long network, int p)
Returns the score of Player p in network. (Either the 13
th or 14
th digits in network.)
(Required) void updateNetwork(long long &network, int pos, int p)
Performs the task of Player p cutting a string in position pos of network. The reference parameter
network should get updated, and if any coins are disconnected, the score of Player p should be
incremented, to reflect the new network configuration.
For example, suppose network is
10010000010110. Then calling updateNetwork(network, 4, 1) means Player 1 cutting the string
in position 4, disconnecting a coin (in the top-right if drawn out). Thus, the function call should update
network to 10000000010120. (Position 4 is updated to 0, and score of Player 1 is increased to 2.)
Note that cutting one string can sometimes disconnect at most two coins. To determine if a new coin
is disconnected, calling the stringStatus(…) function is useful. Besides, you should not print
anything using cout in this function.
In the above functions, you can assume that (a) the parameter network is always a proper encoding
of a game network (14-digit integer; 1
st–12th digits are 0 or 1; 13rd and 14th digits are the scores, etc.);
(b) the parameter pos is always 1–12; and (c) the parameter p is always either 1 or 2.
Program Flow
You should call the functions above to aid your implementation of the following program flow.
1. The program starts the game with a full network (11111111111100). Player 1 takes the first turn.
2. Then, you should prompt the current player to enter an integer to denote the position where s/he
wants to cut a string.
3. A user input is invalid if the input position is not 1–12, or the position was already cut. In case it is
invalid, display a warning message and go back to Step 2.
4. Update the network by cutting the string in the input position.
5. If the current player has disconnected one or more coin(s), print a message and keep him/her the
current player. Otherwise, swap the other player to become the current player.
6. Repeat steps 2 to 5 until all 12 strings have been cut. (That is, until game is over.)
7. Once all strings have been cut, determine the winner or a draw and display the message “Player
1 wins!”, “Player 2 wins!”, or “Draw game!” accordingly.
Other Requirements
You cannot declare any global variables (variables declared outside any functions). You cannot use any
functions in the library. You cannot use any arrays in this assignment.
Program Output
The following shows some sample output of the program. The blue text is user input and the other
text is the program output. You can try the provided sample program for other input. Your program
output should be exactly the same as the sample program (i.e., same text, same symbols, same letter
case, same number of spaces, etc.). Otherwise, it will be considered as wrong, even if you have
computed the correct result.
##########
# | | #
#–$–$–#
# | | #
#–$–$–#
# | | # Player 1 score: 0
########## Player 2 score: 0
Player 1, make your move (1-12): 1
##########
# | #
#–$–$–#
# | | #
#–$–$–#
# | | # Player 1 score: 0
########## Player 2 score: 0
Player 2, make your move (1-12): -1
Invalid. Try again!
Player 2, make your move (1-12): 13
Invalid. Try again!
Player 2, make your move (1-12): 1
Invalid. Try again!
Player 2, make your move (1-12): 12
##########
# | #
#–$–$–#
# | | #
#–$–$–#
# | # Player 1 score: 0
########## Player 2 score: 0
Player 1, make your move (1-12): 2
##########
# #
#–$–$–#
# | | #
#–$–$–#
# | # Player 1 score: 0
########## Player 2 score: 0
Player 2, make your move (1-12): 11
##########
# #
#–$–$–#
# | | #
#–$–$–#
# # Player 1 score: 0
########## Player 2 score: 0
Player 1, make your move (1-12): 3
##########
# #
# $–$–#
# | | #
#–$–$–#
# # Player 1 score: 0
########## Player 2 score: 0
Player 2, make your move (1-12): 10
##########
# #
# $–$–#
# | | #
#–$–$ #
# # Player 1 score: 0
########## Player 2 score: 0
Player 1, make your move (1-12): 6
##########
# #
# $–$–#
# | #
#–$–$ #
# # Player 1 score: 0
########## Player 2 score: 0
Player 2, make your move (1-12): 4
Player 2 scores! Gets another turn.
##########
# #
# $ $–#
# | #
#–$–$ #
# # Player 1 score: 0
########## Player 2 score: 1
Player 2, make your move (1-12): 7
##########
# #
# $ $–#
# #
#–$–$ #
# # Player 1 score: 0
########## Player 2 score: 1
Player 1, make your move (1-12): 9
Player 1 scores! Gets another turn.
##########
# #
# $ $–#
# #
#–$ $ #
# # Player 1 score: 1
########## Player 2 score: 1
Player 1, make your move (1-12): 8
Player 1 scores! Gets another turn.
##########
# #
# $ $–#
# #
# $ $ #
# # Player 1 score: 2
########## Player 2 score: 1
Player 1, make your move (1-12): 5
##########
# #
# $ $ #
# #
# $ $ #
# # Player 1 score: 3
########## Player 2 score: 1
Player 1 wins!
Submission and Marking
Your program file name should be stringcoin.cpp. Submit the file in Blackboard
(https://blackboard.cuhk.edu.hk/).
Insert your name, student ID, and e-mail address as comments at the beginning of your source
file.
You can submit your assignment multiple times. Only the latest submission counts.
Your program should be free of compilation errors and warnings.
Your program should include suitable comments as documentation.
Plagiarism is strictly monitored and heavily punished if proven. Lending your work to others is
subjected to the same penalty as the copier.
Update on 7 Oct:
No need to print “Player x scores! Gets
another turn.” after the last move.
