The repository for Assignment 1, PR2 class, Hanoi University assignment1 (2).pdf
(According to ChatGPT): TextIO can be considered an alternative to Scanner in Java. Both TextIO and Scanner provide methods for reading and writing text, numbers, and other data types from various input/output sources, such as files, console, and strings.
So, these line:
private static final char GREEN = 'G';
/** constant value for the blue bean*/
private static final char BLUE = 'B';
/** constant for removed beans */
private static final char REMOVED = '-';
/** the null character*/
private static final char NULL = '\u0000';Essentially mean that whenever we type GREEN/BLUE/NULL in our code, it'll return G,B.
Meanwhile, these line:
char[][] tins = {
{BLUE, BLUE, BLUE, GREEN, GREEN},
{BLUE, BLUE, BLUE, GREEN, GREEN, GREEN},
{GREEN},
{BLUE},
{BLUE, GREEN}
};This code is initializing a 2-dimensional array of characters called tins. The array tins is an array of arrays, where each sub-array represents a tin of beans. Each sub-array is made up of individual beans represented by characters, where 'B' stands for blue bean, 'G' stands for green bean, and '-' stands for an empty space.
So for example, the first sub-array in tins looks like this:
{BLUE, BLUE, BLUE, GREEN, GREEN}which means that this tin contains 3 blue beans, 2 green beans, and no empty spaces. This array of tins will be used to test the tinGame function in the main method.
#Temp code (as of 2PM, March 16 '23)
package a1_2101040150;
import java.util.Arrays;
import java.util.Random;
import textio.TextIO;
public class CoffeeTinGame {
/** constant value for the green bean*/
private static final char GREEN = 'G';
/** constant value for the blue bean*/
private static final char BLUE = 'B';
/** constant for removed beans */
private static final char REMOVED = '-';
/** the null character*/
private static final char NULL = '\u0000';
/**
* the main procedure
* @effects
* initialise a coffee tin
* {@link TextIO#putf(String, Object...)}: print the tin content
* {@link @tinGame(char[])}: perform the coffee tin game on tin
* {@link TextIO#putf(String, Object...)}: print the tin content again
* if last bean is correct
* {@link TextIO#putf(String, Object...)}: print its colour
* else
* {@link TextIO#putf(String, Object...)}: print an error message
*/
@SuppressWarnings("JavadocReference")
public static void main(String[] args) {
// initialise some beans
char[][] tins = {
{BLUE, BLUE, BLUE, GREEN, GREEN},
{BLUE, BLUE, BLUE, GREEN, GREEN, GREEN},
{GREEN},
{BLUE},
{BLUE, GREEN}
};
for (int i = 0; i < tins.length; i++) {
char[] tin = tins[i];
// expected last bean
// p0 = green parity /\
// (p0=1 -> last=GREEN) /\ (p0=0 -> last=BLUE)
// count number of greens
int greens = 0;
for (char bean : tin) {
if (bean == GREEN)
greens++;
}
// expected last bean
final char last = (greens % 2 == 1) ? GREEN : BLUE;
// print the content of tin before the game
System.out.printf("%nTIN (%d Gs): %s %n", greens, Arrays.toString(tin));
// perform the game
// get actual last bean
char lastBean = tinGame(tin);
// lastBean = last \/ lastBean != last
// print the content of tin and last bean
System.out.printf("tin after: %s %n", Arrays.toString(tin));
// check if last bean as expected and print
if (lastBean == last) {
System.out.printf("last bean: %c%n", lastBean);
} else {
System.out.printf("Oops, wrong last bean: %c (expected: %c)%n", lastBean, last);
}
}
}
private static final String[] BeansBag = new String[30];
static {
int blueCount = 0;
int greenCount = 0;
int spaceCount = 0;
for (int i = 0; i < BeansBag.length; i++) {
if (blueCount < BeansBag.length / 3) {
BeansBag[i] = "blue";
blueCount++;
} else if (greenCount < BeansBag.length / 3) {
BeansBag[i] = "green";
greenCount++;
} else {
BeansBag[i] = "available";
spaceCount++;
}
}
System.out.println("BeansBag: blue=" + blueCount + ", green=" + greenCount + ", available=" + spaceCount);
}
/**
Generates a random integer between 1 and n (inclusive).
@param n the maximum value of the generated integer (exclusive)
@return a random integer between 1 and n (inclusive)
*/
public static int randInt(int n) {
Random rand = new Random();
return rand.nextInt(n);
}
/**
* Performs the coffee tin game to determine the colour of the last bean
*
* @requires tin is not null /\ tin.length > 0
* @modifies tin
* @effects <pre>
* take out two beans from tin
* if same colour
* throw both away, put one blue bean back
* else
* put green bean back
* let p0 = initial number of green beans
* if p0 = 1
* result = `G'
* else
* result = `B'
* </pre>
*/
public static char tinGame(char[] tin) {
while (hasAtLeastTwoBeans(tin)) {
// take two beans from tin
char[] twoBeans = takeTwo(tin);
// process beans to update tin
char b1 = twoBeans[0];
char b2 = twoBeans[1];
// process beans to update tin
if (b1 == b2) {
// put B in bin
putIn(tin, BLUE);
} else { // BG, GB
// put G in bin
putIn(tin, GREEN);
}
}
return anyBean(tin);
}
/**
* @effects
* if tin has at least two beans
* return true
* else
* return false
*/
private static boolean hasAtLeastTwoBeans(char[] tin) {
int count = 0;
for (char bean : tin) {
if (bean != REMOVED) {
count++;
}
if (count >= 2) // enough beans
return true;
}
// not enough beans
return false;
}
/**
* @requires tin has at least 2 beans left
* @modifies tin
* @effects
* remove any two beans from tin and return them
*/
private static char[] takeTwo(char[] tin) {
char first = takeOne(tin);
char second = takeOne(tin);
return new char[]{first, second};
}
/**
* @requires tin has at least one bean
* @modifies tin
* @effects
* remove any bean from tin and return it
*/
public static char takeOne(char[] tin) {
int n = tin.length;
int randomIndex = randInt().applyAsInt(n);
char bean = ' ';
if (randomIndex >= 0 && randomIndex < n) {
bean = tin[randomIndex];
if (bean != REMOVED) {
tin[randomIndex] = REMOVED;
} else {
// try to find another bean
for (int i = 0; i < n; i++) {
bean = tin[i];
if (bean != REMOVED) {
tin[i] = REMOVED;
return bean;
}
}
bean = ' ';
}
}
return bean;
}
// no beans left
return NULL;
}
/**
* @requires tin has vacant positions for new beans
* @modifies tin
* @effects
* place bean into any vacant position in tin
*/
private static void putIn(char[] tin, char bean) {
for (int i = 0; i < tin.length; i++) {
if (tin[i] == REMOVED) { // vacant position
tin[i] = bean;
break;
}
}
}
/**
* @effects
* if there are beans in tin
* return any such bean
* else
* return '\u0000' (null character)
*/
private static char anyBean(char[] tin) {
for (char bean : tin) {
if (bean != REMOVED) {
return bean;
}
}
// no beans left
return NULL;
}
}
// Update 1 (1.08 PM, March 8 23): Remove the utils.IO line, return the following:
/*
TIN (2 Gs): [B, B, B, G, G]
tin after: [B, -, -, -, -]
last bean: B
TIN (3 Gs): [B, B, B, G, G, G]
tin after: [G, -, -, -, -, -]
last bean: G
TIN (1 Gs): [G]
tin after: [G]
last bean: G
TIN (0 Gs): [B]
tin after: [B]
last bean: B
TIN (1 Gs): [B, G]
tin after: [G, -]
last bean: G
Process finished with exit code 0
*/
// Update 2: 2 method tinGame (line 90) and takeOne (line 150) has been updated to PUBLIC .
// Update 3: Create 3 new public procedures (see details below): randInt, getBean, updateTin. In non-nerd langauges, this mean create a METHOD
// Update 4: (12.57 PM, March 14 '23): Add the BeansBag requirement using chatGPT, and temporarily add return 0 to int for the sake of running the code
// Update 5: (1.32 PM, March 14 '23)
/*
- randInt is modified to completed in code
- no import by scanner is allowed.
- after running BeansBag, add a new line: BEANS_BAG: blue=10, green=10, available=10. This is consistent with PR2 requirements.
*/
// Update 6: takeOne modified
// Update 7: A lot of bugs. Haiyaa. Return to the original design/implementation for detail.
awss- Holy shit this assignment got a 9.5 out of 10. I sometimes have no idea how the world works.
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