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Creating a non-Attacking Queens game that is supposed to print out all 92 solutions of 8 queens on a chess board that cannot attack eachother

I made the 8x8 chess board and have a lot of the code done, but for some reason it only print out one solution, does anyone know why this may be and how I can fix it?
public class NonAttackingQueens {
private int[][] board;
private int solutionCount = 0;
private boolean solutionFound = false;
public NonAttackingQueens() {
board = new int[8][8];
}
public boolean canPlace(int x, int y) {
// Check if a queen is already placed at position (x, y)
if (board[x][y] == 1) {
return false;
}
// Check horizontal positions
for (int i = 0; i < 8; i++) {
if (board[x][i] == 1) {
return false;
}
}
// Check vertical positions
for (int i = 0; i < 8; i++) {
if (board[i][y] == 1) {
return false;
}
}
// Check diagonal positions
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
if (board[i][j] == 1 && (Math.abs(i - x) == Math.abs(j - y))) {
return false;
}
}
}
return true;
}
public void solve() {
// Check if the solutionCount has reached 92
if (solutionCount == 92) {
return;
}
// Check if all 8 queens have been placed
int queensPlaced = 0;
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
if (board[i][j] == 1) {
queensPlaced++;
}
}
}
if (queensPlaced == 8) {
// All positions have been checked, so we have found a solution
solutionCount++;
System.out.println("Solution " + solutionCount + ":");
print();
return;
}
// Try to place a queen at each position on the board
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
if (canPlace(i, j)) {
// Place a queen at position (i, j) and try to solve the rest of the board
board[i][j] = 1;
solve();
// Backtrack: remove the queen from position (i, j) and try the next position
board[i][j] = 0;
}
}
}
}
public void print() {
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 8; j++) {
if (board[i][j] == 1) {
System.out.print(" X");
} else {
System.out.print(" O");
}
}
System.out.println();
}
System.out.println("---------------");
}
}
I'm doing this in blueJ, so I tried to run the void solve(); method and it runs, but it only prints out the first of 92 solutions 92 times. It should print out all 92 different solutions.

How I can read how many mines are around each empty cell.Game minesweeper

The program below ask the user how many mines he wants to see on the field and then display the field with mines.
In next step I need to calculate how many mines are around each empty cell. And I know that I
need to check 8 cells if the cell is in the middle, 5 cells if the cell is in the side, and 3
cells if the cell is in the corner. If there are from 1 to 8 mines around the cell, I need to
output the number of mines instead of the symbol representing an empty cell.
import java.util.Scanner;
import java.util.Random;
public class Minesweeper {
char[][] minesweeper = new char[9][9];
Random randNum = new Random();
Scanner sc = new Scanner(System.in);
public Minesweeper() {
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
minesweeper[i][j] = '*';
}
}
}
public void printMinesweeper() {
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
System.out.print(minesweeper[i][j]);
}
System.out.println();
}
}
public void randomX() {
System.out.print("How many mines do you want on the field?: ");
int numberOfMines = sc.nextInt();
int i = 0;
while (i < numberOfMines) {
int x = randNum.nextInt(9);
int y = randNum.nextInt(9);
if (minesweeper[x][y] == '*') {
minesweeper[x][y] = 'X';
i++;
}
}
printMinesweeper();
}
}

You can do it like this:
import java.util.Random;
import java.util.Scanner;
public class Minesweeper {
public static void main(String[] args) {
Minesweeper minesweeper = new Minesweeper();
minesweeper.randomX();
minesweeper.printMinesweeper();
}
char[][] minesweeper = new char[9][9];
Random randNum = new Random();
Scanner sc = new Scanner(System.in);
public Minesweeper() {
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
minesweeper[i][j] = '*';
}
}
}
public void printMinesweeper() {
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
System.out.print(getCharAt(i, j));
}
System.out.println();
}
}
private String getCharAt(int i, int j) {
if (mineAt(i, j)) {
return "X";
}
int minesNear = countMinesNear(i, j);
return Integer.toString(minesNear);
}
private boolean mineAt(int i, int j) {
return minesweeper[i][j] == 'X';
}
private int countMinesNear(int i, int j) {
int mines = 0;
for (int x = -1; x <= 1; x++) {//near fields in x direction
for (int y = -1; y <= 1; y++) {//near fields in y direction
if (x + i >= 0 && x + i < minesweeper.length && y + j >= 0 && y + j < minesweeper.length) {//check whether the field exists
if (minesweeper[x+i][y+j] == 'X') {//check whether the field is a mine
mines++;
}
}
}
}
return mines;
}
public void randomX() {
System.out.print("How many mines do you want on the field?: ");
int numberOfMines = sc.nextInt();
int i = 0;
while (i < numberOfMines) {
int x = randNum.nextInt(9);
int y = randNum.nextInt(9);
if (minesweeper[x][y] == '*') {
minesweeper[x][y] = 'X';
i++;
}
}
printMinesweeper();
}
}
The countMinesNear(int, int) method check whether the field near exists (to prevent index errors on the edges) and counts the mines if the fields exist.

I am trying this simple sudoku

I am trying a simple sudoku program. i started by taking the values in a 3D
array and then copied them into a 1D array by using mr.serpardum's method.
i know that there is an error at the point where i am trying to find
duplicate elements,because even if i give same numbers as input the output
says "its a sudoku" but i can't to find it...apparently i can't add any
image coz i dont have enough credits
public class SecondAssignment {
#SuppressWarnings("unused")
public static void main(String[] args) throws IOException {
int i = 0, j = 0, k = 0;
boolean result = false;
int arr1[][];
arr1 = new int[3][3];
int arr2[];
arr2 = new int[9];
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the elements in the sudoku block");
//getting elements into array
for (i = 0; i < 3; i++) {
for (j = 0; j < 3; j++) {
arr1[i][j] = Integer.parseInt(br.readLine());
}
}
//printing it in matrix form
for (i = 0; i < 3; i++) {
for (j = 0; j < 3; j++) {
System.out.print(arr1[i][j] + "\t");
}
System.out.println(" ");
}
//copying array1 elements into array 2
for (i = 0; i < 3; i++) {
for (j = 0; j < 3; j++) {
arr2[i * 3 + j] = arr1[i][j];
}
}
//finding duplicate elements
for (i = 0; i < arr2.length; i++) {
for (int m = i + 1; m < arr2.length; m++) {
if (arr2[i] == (arr2[m])) {
System.out.println("Not a sudoku");
//result = true;
} else {
System.out.println("Its a sudoku");
//result = false;
}
}
}
}
}

You can update your code to following
//finding duplicate elements
for( i = 0; i < arr2.length; i++){
for(int m = i+1; m < arr2.length; m++){
if(arr2[i] == (arr2[m])){
result = true;
break;
}
}
}
if(result){
System.out.println("\nNot a sudoku");
}
else{
System.out.println("\nIts a sudoku");
}
You should have used break as soon as the match was found.
This code just checks if duplicate element is present in the array (of size 9) or not.

Problems with refactoring java code

I am doing my homework right now and have a question about refactoring my code in Java.
I am working on a Sudoku right now and I need to check if the 3x3 boxes are valid or not. To do that I create a one dimensional array with all the numbers of the boxes and later I compare the value of them. It is working right now but it really isn't refactored at all. I would really like to know if there is any way to reduce all this copy paste.
public static boolean validFieldParts() {
int counter = 0;
boolean isValid = false;
int[] copyArray1 = new int[field.length];
int[] copyArray2 = new int[field.length];
int[] copyArray3 = new int[field.length];
int[] copyArray4 = new int[field.length];
int[] copyArray5 = new int[field.length];
int[] copyArray6 = new int[field.length];
int[] copyArray7 = new int[field.length];
int[] copyArray8 = new int[field.length];
int[] copyArray9 = new int[field.length];
// copy the array
// 1 große Feld
for (int i = 0; i < field.length / 3; i++) {
for (int j = 0; j < field[i].length / 3; j++) {
copyArray1[i * 3 + j] = field[i][j];
}
}
// 2 große Feld
for (int i = 0; i < field.length / 3; i++) {
for (int j = 3; j < 6; j++) {
copyArray2[i * 3 + j - 3] = field[i][j];
}
}
// 3 große Feld
for (int i = 0; i < field.length / 3; i++) {
for (int j = 6; j < 9; j++) {
copyArray3[i * 3 + j - 6] = field[i][j];
}
}
// 4 große Feld
for (int i = 3; i < 6; i++) {
for (int j = 0; j < field[i].length / 3; j++) {
copyArray4[(i - 3) * 3 + j] = field[i][j];
}
}
// 5 große Feld
for (int i = 3; i < 6; i++) {
for (int j = 3; j < 6; j++) {
copyArray5[(i - 3) * 3 + j - 3] = field[i][j];
}
}
// 6 große Feld
for (int i = 3; i < 6; i++) {
for (int j = 6; j < 9; j++) {
copyArray6[(i - 3) * 3 + j - 6] = field[i][j];
}
}
// 7 große Feld
for (int i = 6; i < 9; i++) {
for (int j = 0; j < field[i].length / 3; j++) {
copyArray7[(i - 6) * 3 + j] = field[i][j];
}
}
// 8 große Feld
for (int i = 6; i < 9; i++) {
for (int j = 3; j < 6; j++) {
copyArray8[(i - 6) * 3 + j - 3] = field[i][j];
}
}
// 9 große Feld
for (int i = 6; i < 9; i++) {
for (int j = 6; j < 9; j++) {
copyArray9[(i - 6) * 3 + j - 6] = field[i][j];
}
}
Arrays.sort(copyArray1);
Arrays.sort(copyArray2);
Arrays.sort(copyArray3);
Arrays.sort(copyArray4);
Arrays.sort(copyArray5);
Arrays.sort(copyArray6);
Arrays.sort(copyArray7);
Arrays.sort(copyArray8);
Arrays.sort(copyArray9);
for (int i = 1; i < copyArray1.length; i++) {
if (copyArray1[i] == copyArray1[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray2.length; i++) {
if (copyArray2[i] == copyArray2[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray3.length; i++) {
if (copyArray3[i] == copyArray3[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray4.length; i++) {
if (copyArray4[i] == copyArray4[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray5.length; i++) {
if (copyArray5[i] == copyArray5[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray6.length; i++) {
if (copyArray6[i] == copyArray6[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray7.length; i++) {
if (copyArray7[i] == copyArray7[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray8.length; i++) {
if (copyArray8[i] == copyArray8[i - 1])
counter++;
else
continue;
}
for (int i = 1; i < copyArray9.length; i++) {
if (copyArray9[i] == copyArray9[i - 1])
counter++;
else
continue;
}
if (counter > 0)
isValid = false;
else
isValid = true;
return isValid;
}

Instead of using 9 different arrays and 9 different loops to represent each section of 9, I would have another nested for loop that iterates over each cluster using the same array.
//Iterate over each 'block'
for (int row = 0; row < 3; row++) {
for (int col = 0; col < 3; col++) {
//Iterate over each cell in the block
for (int i = row*3; i < (row+1)*3; i++) {
for (int j = col*3; j < (col+1)*3; j++) {
copyArray[(i - 3) * 3 + j - 3] = field[i][j];
}
}
//Sort array and do duplication check here - return false if dupe found
}
}
return true
This would cut down on the length of your code, although it may not be more efficient.
Instead of using a counter flag, it would be much faster to instead return false whenever you would have incremented the counter, and to return true at the end. This would prevent unnecessary code from running

Here a complete refactoring. Here the improuvements:
Created two new methods: createCopy and isValid
Deleted unused variables counter and isValid
Substituted 9 arrays with one two size array.
The code as not been tested, please take a bit careful attention on method createCopy in particular.
// Creates each block of 9 digits copying digits from field
// row, col are the block position, starting from upper left 0, 0 to
// last block 2, 2
public static int[] createCopy(int[] field, int row, int col) {
int[] copy = new int[9];
for (int i = 3 * row; i < 3 * row + 3; i++) {
for (int j = 3 * col; j < 3 * col + 3; j++) {
copy[(i - 3 * row) * 3 + j - 3 * col] = field[i][j];
}
}
return copy;
}
// Check if one block is valid
private static boolean isValid(int[] copyArray) {
Arrays.sort(copyArray);
for (int i = 1; i < copyArray.length; i++) {
if (copyArray[i] == copyArray[i - 1]) {
// Exit immediately if not valid
return false;
}
}
return true;
}
// Create blocks, then validate them
// At first not valid block return false
public static boolean validFieldParts() {
int[][] copyArrays = new int[3][3];
for (int row = 0; row < 3; row++) {
for (int col = 0; col < 3; col++) {
copyArrays[row][col] = createCopy(field, row, col);
}
}
for (int[] copyArray : copyArrays) {
if (!isValid(copyArray)) {
// Exit immediately if not valid
return false;
}
}
return true;
}

Main class in Game Of Life isn't working [closed]

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 8 years ago.
Improve this question
I was trying to solve the Game of life problem for a teacher. Rules of that game are:
Any live cell with fewer than two live neighbors dies, as if caused by under-population. Any live cell with two or three live neighbors’ lives on to the next generation. Any live cell with more than three live neighbors dies, as if by overcrowding. Any dead cell with exactly three live neighbors becomes a live cell, as if by reproduction.
There are two problems with my code - first of all, my main class doesn't seem to be working. Secondly, I performed the problem through many many if else statements. Are there more concise ways of writing the exceptions for my getNeighbors() method?
Thanks!
import java.util.Random;
public class GameOfLife {
final static int ROWS = 6;
final static int COLUMNS = 7;
String[][] simulator;
private Random randomGenerator;
public GameOfLife() {
simulator = new String[ROWS][COLUMNS];
randomGenerator = new Random();
}
public void fillSpot (int row, int column) {
simulator [row][column] = "O";
}
private void deleteSpot (int row, int column) {
simulator[row][column] = "";
}
// Do I need the above methods? really?
public void randomSimulation() {
for (int i = 0; i <= ROWS; i++) {
for (int j = 0; j <= COLUMNS; j++) {
int random = randomGenerator.nextInt(1);
if (random == 1) {
fillSpot(i,j);
}
}
}
}
private void getNeighbors (int row, int column) {
int neighbors = 0;
if (row < ROWS && row > 0 && column < COLUMNS && column > 0) {
for (int i = row - 1; i <= row + 1; i++) {
for (int j = column - 1; j <= column + 1; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
if (row > ROWS || column > COLUMNS || row < 0 || column < 0) {
}
else if (row == ROWS && column < COLUMNS && column != 0) {
for (int i = row - 1; i <= ROWS; i++) {
for (int j = column - 1; j <= column + 1; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
else if (row < ROWS && column == COLUMNS && row != 0) {
for (int i = row - 1; i <= row + 1; i++) {
for (int j = column - 1; j <= COLUMNS; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
else if (row == 0 && column < COLUMNS && column != 0) {
for (int i = 0; i <= row + 1; i++) {
for (int j = column - 1; j <= COLUMNS + 1; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
else if (row == 0 && column == COLUMNS) {
for (int i = row; i <= row + 1; i++) {
for (int j = column - 1; j <=COLUMNS; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
else if (column == 0 && row < ROWS && row != 0) {
for (int i = row - 1; i <= row + 1; i++) {
for (int j = column; j <= COLUMNS + 1; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
else {
for (int i = row; i <= row + 1; i++) {
for (int j = column; j <= column + 1; j++) {
String temp = simulator[i][j];
if (temp.contains("O")) {
neighbors++;
}
}
}
}
// for row == 0 && column == 0
if (simulator [row][column].contains("O")) {
neighbors--;
}
simulator[row][column] += " " + neighbors;
}
//There are wayyy too manyy clauses here for me to be comfortable. There's got to be a way to do this cleaner
private void nextGenPlanning() {
for (int i = 0; i <= ROWS; i++) {
for (int j = 0; j <= COLUMNS; j++) {
getNeighbors(i,j);
}
}
}
private void nextGen() {
nextGenPlanning();
for (int i = 0; i <= ROWS; i++) {
for (int j = 0; j <= COLUMNS; j++) {
String temp = simulator[i][j];
if (temp.charAt(temp.length()) <= 1 || temp.charAt(temp.length()) >= 4) {
deleteSpot(i,j);
}
else {
fillSpot (i,j);
}
}
}
}
public String toString() {
String string = "";
for (int i = 0; i < ROWS; i++) {
string = string + "|";
for (int j = 0; j < COLUMNS; j++) {
String temp = simulator[i][j];
string = string + temp.charAt(0);
}
string = string + "|\n";
}
return string;
}
public String simulate (int numOfTrials) {
String string = "";
for (int i = 0; i <= numOfTrials; i++) {
nextGen();
string += toString();
}
return string;
}
public void main (String [] args) {
randomSimulation();
System.out.println(simulate(2));
}
}

First, you have:
public void main (String [] args) {
randomSimulation();
System.out.println(simulate(2));
}
You should have:
public static void main (String[] args) {
GameOfLife game = new GameOfLife();
game.randomSimulation();
System.out.println(game.simulate(2));
}
Second, for getNeighbors, first consider that a 'get' method usually returns a value. If you're counting the number of neighbors, consider:
public int getNeighbors(int x, int y) {
int neighbors = 0;
int leftX = Math.max(x-1, 0);
int rightX = Math.min(x+1, COLUMNS);
int topY = Math.max(y-1, 0);
int bottomY = Math.min(y+1, ROWS);
for (int i=leftX; i < rightX; i++) {
for (int j=topY; j < bottomY; j++) {
if (simulator[i][j].contains('O')) { // Notice I'm using a char here, see my next comment
neighbors++;
}
}
}
return neighbors;
}
Third, I recommend using char[][] instead of String[][] for your simulator if each space in the simulator only holds one character value. There are some things about Strings in Java that you don't need to get tripped up with - for example, in Java, you cannot compare the value of Strings using == (you need to use String's equals() method).

First , your main class should be Public static void main(String[] args) and you can use switch case except of if else if you really sure on if else you can use if ( blabla == blablabla &(this means and ) blaba == babalaba)