Assignment 3: Strings and Coins

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.

CSCI1120 Introduction to Computing Using C++, Fall 2018-2019

Department of Computer Science and Engineering, The Chinese University of Hong Kong

₁₄ 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–12^th digits are 0 or 1; 13^rd and 14^th 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.