We Keep Coding

How to find duplicates in a submatrices of 2d matrix and compare them

I have a question. Can anyone help me with finding duplicates in submatrices?
I have a code which finds submatrices in 2d matrix, but I can't find duplicates. I thought to push the values onto the Stack (because in assignment I should use Stack), find all duplicates in each submatrix, and then compare them, but I don't really know how to do it. I'll be very gratefull, if anyone help me to finish this program.
My code:
public static void main(String[] args) throws Exception {
int[][] data = new int[3][3];
Random random = new Random();
for(int i=0; i<data.length;i++)
{
for(int j=0; j<data.length; j++)
{
data[i][j] = random.nextInt(10);
}
}
printSubMatrix(data);
}
private static void printSubMatrix(int[][] mat) {
int rows=mat.length;
int cols=mat[0].length;
Stack _stack = new Stack();
//prints all submatrix greater than or equal to 2x2
for (int subRow = rows; subRow >= 2; subRow--) {
int rowLimit = rows - subRow + 1;
for (int subCol = cols; subCol >= 2; subCol--) {
int colLimit = cols - subCol + 1;
for (int startRow = 0; startRow < rowLimit; startRow++) {
for (int startCol = 0; startCol < colLimit; startCol++) {
for (int i = 0; i < subRow; i++) {
for (int j = 0; j < subCol; j++) {
System.out.print(mat[i + startRow][j + startCol] + " ");
_stack.push(mat[i+startRow][j+startCol]);
}
System.out.print("\n");
}
System.out.print("\n");
}
}
}
}
System.out.printf(_stack.toString().replaceAll("\\[", "").replaceAll("]", ""));
}

different output in conways game of life

I have to create a Java program for Conway's Game Of Life in procedural manner and I'm only one step away from finishing - all I have left to do is figure out how to make the output change itself(something like a GIF). Instead, my program outputs all the results one by one. I'm figuring it should be some kind of a loop, but I'm not sure. Here's the code:
import java.util.Random;
import java.util.Scanner;
class gameOfLife {
public static void main(String[] args) {
//User input
Scanner in = new Scanner(System.in);
System.out.println("How many rows?");
int rows = in.nextInt();
System.out.println("How many columns?");
int cols = in.nextInt();
//Declaring variables and grids
int[][] grid = new int[rows][cols];
int[][] nextGrid = new int[rows][cols];
int[][] temp = new int [rows][cols];
//Initializing first generation
initiateGrid(grid);
printGameBoard(grid);
//Looping through 10 generations
for (int x = 0; x < 20; x++) {
applyTheRules(grid, rows, cols, nextGrid);
temp = nextGrid;
nextGrid = grid;
grid = temp;
printGameBoard(grid);
}
}
//Initiating first generation grid randomly
static void initiateGrid(int[][] grid) {
Random r = new Random();
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[i].length; j++) {
grid[i][j] = r.nextInt(2);
}
}
}
//Printing out the game board
static void printGameBoard(int[][] grid) {
for (int i = 0; i < grid.length; i++) {
for (int j = 0; j < grid[i].length; j++) {
if (grid[i][j] == 0)
System.out.print(" . ");
else
System.out.print(" ■ ");
}
System.out.println();
}
System.out.println();
}
//Applying the rules of the game
static void applyTheRules(int [][] grid, int rows, int cols, int [][] nextGrid) {
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
int count = 0;
if(i-1>=0 && i+1<grid.length && j-1>=0 && j+1<grid[i].length) {
for (int x = -1; x <= 1; x++) {
for (int y = -1; y <= 1; y++) {
count += grid[i + x][j + y];
}
}
count -= grid[i][j];
} else{
for (int x = -1; x <= 1; x++) {
for (int y = -1; y <= 1; y++) {
count += 0;
}
}
}
//Alive cell becomes dead, if there are more than
//3 or less than 2 neighbouring cells
if((grid[i][j]==1)&&(count<2)||(count>3))
nextGrid[i][j]=0;
//Dead cell becomes alive if there are exactly 3 neighbouring cells
else if((grid[i][j]==0)&&(count==3))
nextGrid[i][j]=1;
//State stays the same
else
nextGrid[i][j]=grid[i][j];
}
}
}
}

Strange (to me) looping error

I just got some help here for index out of bounds and you guys were wonderful. I added to account for the direction change in my battleship game by adding the following lines of code
if(direction == 1){
and
}else{
in the following code. It went from working perfectly to looping constantly though can you guys give me an idea as to why this is happening?
package outlab6;
import java.util.Scanner;
public class Battleship {
private int rows;
private int cols;
private Spot spot[][];
Scanner input = new Scanner(System.in);
public Battleship(int rows, int cols){
this.rows = rows;
this.cols = cols;
}
public void setBoard(){
spot = new Spot[rows][cols];
for(int i = 0; i < rows; i++){
for( int j = 0; j < cols; j++){
spot[i][j] = new Spot();
}
}
//setup board to be completely empty
for(int i = 0; i < rows; i++){
for(int j = 0; j < cols; j++){
spot[i][j].setShip(0);
}
}
// //test code
// for(int i = 0; i < rows; i++){
// for(int j = 0; j < cols; j++){
// System.out.print(spot[i][j].getShip());
// }
// System.out.println();
// }
setShips();
}
public void printBoard(boolean active){
}
public boolean over() {
return false;
}
public void makeGuess() {
input.nextInt();
}
public void printStatistics() {
}
public void setShips(){
//this method creates and places the ships
//start with carrier and move on down
for(int i = 5; i > 1; i--){
int col;
int row;
boolean valid = false;
//set a direction
int direction = (int)(Math.random()*2)+1;
//System.out.println(direction);
//get a valid spot
while(!valid){
//generate a location
int chosenRow = (int)(Math.random()* rows);
int chosenCol = (int)(Math.random()* cols);
System.out.println("Row:" + chosenRow);
System.out.println("Col:" + chosenCol);
//check to see if spot is open
if(direction == 1){
//for horizontal ships
if(chosenCol + i < cols){
for(int j = 0; j < i; j++){
if(spot[chosenRow][chosenCol + i].getShip() == 0){
valid = true;
}else{
valid = false;
}
}
}else{
//go through again
}
}else{
}
}
}
}
}

Think about when your while loop exits? It will exit as soon as valid will become true. And now think about when it will become true. This will only happen if your direction equals 1. And then look at where your direction is set and what possible values direction might take. And voila there is your infinte loop.

If you remove the *2 from direction you'll be fine. Right now it's set to 2 (try pasting System.out.println("Dir:" + direction);
If you remove the *2, you get the following output (when printing direction):
Row:2
Col:3
Dir:1
etc...
Also 1 more tip:
In your setBoard() you do the 2 loops: create spots and make them empty. Why not either create them empty in the constructor or make them empty in the same loop?
public void setBoard(){
spot = new Spot[rows][cols];
for(int i = 0; i < rows; i++){
for( int j = 0; j < cols; j++){
spot[i][j] = new Spot();
spot[i][j].setShip(0);
}
}
}

Filling a ragged array with a loop in java

I was wondering how it was possible to fill a ragged array with a loop in Java.
In my example I want to put Pascals Triangle in the Array. When I try to do it ragged, (
// int [][] hako = new int [n][]; -> as I understand it; it gives a java.lang.NullPointerException.
Thanks
int n = 12, r = 1;
int [][] hako = new int [n][];
for(int i = 0; i < n; i++){
for(int j = 0; j < r; j++){
hako[i][j] = newton(i, j);
}
r++;
}
static int factorial(int n){
int k = 1;
if(n == 0)
return 1;
while(n>1){
k*=n;
n--;
}
return k;
}
static int newton(int i, int j){
return factorial(i)/((factorial(j))*(factorial(i-j)));
}

You need to initialize hako[i] as an array before you can assign a variable to an index within it i.e. hako[i][j].
int n = 12, r = 1;
int [][] hako = new int [n][];
for(int i = 0; i < n; i++){
for(int j = 0; j < r; j++){
// need to initialize hako[i]
hako[i] = new int[r];
hako[i][j] = newton(i, j);
}
r++;
}

your hako, is a matrix, but you initialize only one dimension thus your NullPointerException
to fix it try
for(int i = 0; i < n; i++){
hako[i] = new int[r];
for(int j = 0; j < r; j++){
hako[i][j] = newton(i, j);
}
r++;
}

public static void main(String[] args) {
int y[][] = new int[4][];
int four =4;
for (int row = 0; row < y.length; row++) {
y[row] = new int[four--];
}
RaggedArray(y);
for (int row = 0; row < y.length; row++) {
for (int column = 0; column < y[row].length; column++) {
System.out.print(y[row][column] + " ");
}
System.out.println();
}
}
public static void RaggedArray(int x[][]) {
int j;
for (int i = 0; i < x.length; i++) {
int k=1;
for (j = 0;j<x[i].length ; j++) {
x[i][j] = k++;
}
}
}}
You can change the size and fill it with any data. I wish it will be useful for u and anyone see this code.

Trouble printing chars thru a 2 dim java array

I tried to run this code as a score table where I have chars and ints as below for heading;
A B c
1
2 65 //this is where I'm stuck again!
3
In order to print the score like (65) above in a particular place (matrix) but as soon as I try to add the print statements the table falls apart. Any help would be appreciated;
public class Table3 {
static int[][] list = new int[4][4];
//private char column = 'A';
//private int row = 1;
private static int row = 1;
public Table3(){
//column = 'A';
for (int i = 0; i < 4; i++) {
for (int j = 1; j < 4; j++)
list[i][j] = 0;
}
}
public static void table(char col, int row, int value) {
//System.out.printf("\n\n%s\n", "Table");
for (int i = 1; i < 4; i++) {
System.out.print(row + " ");
row++;
for (int j = 1; j < 4; j++)System.out.print(col + " ");
System.out.println("\n");
col++;
if (row >= 0 && row <= 4 && col >=0 && col <= 4)
System.out.print(list[col][row]=value);
System.out.println("\n");
}
}
}
Client
public class TableTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
Table3 t = new Table3();
t.table('A', 5, 5);
}
}

Learn how to use System.out.printf. The docs are here.
public class Table3
{
static int numRows = 4;
static int numCols = 4;
static int[][] list = new int[numRows][numCols];
public Table3()
{
//column = 'A';
for (int i = 0; i < 4; i++)
{
//this is the row number so you don't have to print it manually
//just print the array
list[i][0] = i;
//initialize the list to 0
for (int j = 1; j < 4; j++)
{
list[i][j] = 0;
}
}
}
public static void table(char col, int row, int value)
{
list[row][col] = value;
int columnWidth = 5; //in characters
//empty space before first column header
for (int i = 0; i < columnWidth; i++)
{
System.out.print(" ");
}
//print the column headers (A through C)
for (int i = 1; i < numCols; i++)
{
System.out.printf("%-" + columnWidth" + "c", (char)(64 + i));
}
System.out.println(); //get off of the column header row
//print the rest of the table
for (int i = 1; i < numRows; i++)
{
for (int j = 0; j < numCols; j++)
{
if (list[i][j] == 0)
{
System.out.printf("%" + columnWidth + "s", " ");
}
else
{
System.out.printf("%-" + columnWidth + "d", list[i][j]);
}
}
System.out.println("\n");
}
}
}