I have coded for Sudoku puzzle in java.The thing is my code has limitation for giving inputs for 9*9 grid.How do I make my code adaptable for all the grids.Please have patience.I am new to java.

What changes do I need to make so that the code can run on all grid sizes?The grid is square not a rectangle.

class Solution { public void solveSudoku(char[][] board) { if(solveSudoku2(board)) { return; } } public boolean solveSudoku2(char[][] board) { boolean isEmpty = true; int row = -1; int col = -1; int n = board.length; //this code is used to check if there exists any empty cell in sudoku board //if there is any empty cell, that means we are not done yet and we need to solve it further, // so we cannot return true at any point until all the cells are full //by empty cell, I mean cells having '.' as the value for(int i = 0; i < board.length; i++) { for(int j = 0; j < board[0].length; j++) { if(board[i][j] == '.') { row = i; col = j; isEmpty = false; break; } } if(!isEmpty) { break; } } if(isEmpty) { return true; } //loop for all the numbers and start placing in the empty cells //numbers start from 1 to n for(int num = 1; num <= n; num++) { //convert number to char char char_num = (char)(num + '0'); //check if the number we are adding satisfies all the sudoku rules, // if it does, then we place that number in the cell if(checkSafe(board,char_num,row,col)) { board[row][col] = (char)(num + '0'); //using this number in place row,col, we check for all the other empty places and see if the board is returning true or not // if the board is not filled that means that we need to use other number in row,col place. //hence backtrack. if(solveSudoku2(board)) { return true; } else { board[row][col] = '.'; } } } return false; } public boolean checkSafe(char[][] board, char num, int row, int col) { //checkk if num is present in the row for(int i = 0; i< board.length; i++ ) { if(board[row][i] == num) { return false; } } for(int j = 0; j < board[0].length; j++) { if(board[j][col] == num) { return false; } } int checknum = (int)Math.sqrt(board.length); //check for the current grid. grid will be basically checknum*checknum matrix. where every matrix will start from startrow to startrow + checknum having checknum length. // so, we we have row = 0, then matrix will start from 0 to 2, i.e. the first 3x3 matrix. // however, we have row = 2, then also the matrix will start from 0 to 2 - the first 3x3 matrix. //however, if row = 3, then we will start our matrix from 3 and cotinute upto 5. int startrow = row - row % checknum; int startcol = col - col % checknum; for(int k = startrow; k < startrow + checknum; k++) { for(int l = startcol; l < startcol + checknum; l++) { if(board[k][l] == num) { return false; } } } return true; } }