I'm trying to make a Sudoku game for my project but if i increase the number of empty spaces in the Sudoku Grid the code just throws an exception arrayoutofbounds but can't figure out where it's coming from. k is the number of empty spaces in the grid.
I haven't tried anything because can't figure out what can be done at this kind of problem
Here is the code:
package sudoku.puzzle;
import java.util.*;
public class SudokuPuzzle {
int[] mat[];
int N; // number of columns/rows.
int SRN; // square root of N
int K; // No. Of missing digits
// Constructor
SudokuPuzzle(int N, int K) {
this.N = N;
this.K = K;
// Compute square root of N
Double SRNd = Math.sqrt(N);
SRN = SRNd.intValue();
mat = new int[N][N];
}
// Driver code
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.println("Select Level Of Difficulty \n 1.Easy\n 2.Medium\n 3.Hard");
String Choice = in .next(); in .close();
if ("1".equals(Choice) || "Easy".equals(Choice) || "easy".equals(Choice) || "e".equals(Choice) || "E".equals(Choice)) {
int N = 9, K = 40;
SudokuPuzzle sudoku = new SudokuPuzzle(N, K);
sudoku.fillValues();
sudoku.printSudoku();
}
if ("2".equals(Choice) || "Medium".equals(Choice) || "medium".equals(Choice) || "m".equals(Choice) || "M".equals(Choice)) {
int N = 9, K = 60;
SudokuPuzzle sudoku = new SudokuPuzzle(N, K);
sudoku.fillValues();
sudoku.printSudoku();
}
if ("3".equals(Choice) || "Hard".equals(Choice) || "hard".equals(Choice) || "h".equals(Choice) || "H".equals(Choice)) {
int N = 9, K = 72;
SudokuPuzzle sudoku = new SudokuPuzzle(N, K);
sudoku.fillValues();
sudoku.printSudoku();
}
}
// Sudoku Generator
public void fillValues() {
// Fill the diagonal of SRN x SRN matrices
fillDiagonal();
// Fill remaining blocks
fillRemaining(0, SRN);
// Remove Randomly K digits to make game
removeKDigits();
}
// Fill the diagonal SRN number of SRN x SRN matrices
void fillDiagonal() {
for (int i = 0; i < N; i = i + SRN)
// for diagonal box, start coordinates->i==j
fillBox(i, i);
}
// Returns false if given 3 x 3 block contains num.
boolean unUsedInBox(int rowStart, int colStart, int num) {
for (int i = 0; i < SRN; i++)
for (int j = 0; j < SRN; j++)
if (mat[rowStart + i][colStart + j] == num)
return false;
return true;
}
// Fill a 3 x 3 matrix.
void fillBox(int row, int col) {
int num;
for (int i = 0; i < SRN; i++) {
for (int j = 0; j < SRN; j++) {
do {
num = randomGenerator(N);
}
while (!unUsedInBox(row, col, num));
mat[row + i][col + j] = num;
}
}
}
// Random generator
int randomGenerator(int num) {
return (int) Math.floor((Math.random() * num + 1));
}
// Check if safe to put in cell
boolean CheckIfSafe(int i, int j, int num) {
return (unUsedInRow(i, num) &&
unUsedInCol(j, num) &&
unUsedInBox(i - i % SRN, j - j % SRN, num));
}
// check in the row for existence
boolean unUsedInRow(int i, int num) {
for (int j = 0; j < N; j++)
if (mat[i][j] == num)
return false;
return true;
}
// check in the row for existence
boolean unUsedInCol(int j, int num) {
for (int i = 0; i < N; i++)
if (mat[i][j] == num)
return false;
return true;
}
// A recursive function to fill remaining
// matrix
boolean fillRemaining(int i, int j) {
// System.out.println(i+" "+j);
if (j >= N && i < N - 1) {
i = i + 1;
j = 0;
}
if (i >= N && j >= N)
return true;
if (i < SRN) {
if (j < SRN)
j = SRN;
} else if (i < N - SRN) {
if (j == (int)(i / SRN) * SRN)
j = j + SRN;
} else {
if (j == N - SRN) {
i = i + 1;
j = 0;
if (i >= N)
return true;
}
}
for (int num = 1; num <= N; num++) {
if (CheckIfSafe(i, j, num)) {
mat[i][j] = num;
if (fillRemaining(i, j + 1))
return true;
mat[i][j] = 0;
}
}
return false;
}
// Remove the K no. of digits to
// complete game
public void removeKDigits() {
int count = K;
while (count != 0) {
int cellId = randomGenerator(N * N);
// System.out.println(cellId);
// extract coordinates i and j
int i = (cellId / N);
int j = cellId % 9;
if (j != 0)
j = j - 1;
// System.out.println(i+" "+j);
if (mat[i][j] != 0) {
count--;
mat[i][j] = 0;
}
}
}
// Print sudoku
public void printSudoku() {
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++)
System.out.print(mat[i][j] + " ");
System.out.println();
}
System.out.println();
}
}
What you got is probably a ArrayIndexOutOfBoundsException. That means at some point you try to access a field of an array outside its boundaries.
But I can´t see where K could be responsible for that. Can you provide more information about the error? E.g. at which value you get it or in which line.
EDIT: The variable i int the removeKDigits() function exceeds the boundaries of the array if the random generator spits out the value 81.