import java.util.LinkedList; import java.util.Queue; import java.util.Stack; class Sudoku_Solver_question { public static int type = 0; public static int height = 0; // Node exploration holds the sudoku board in every iteration private static class Exploration { char[][] board; int curCell = 0; // constructor method public Exploration(char[][] board, int curCell) { this.board = cloneBoard(board); this.curCell = curCell; } // clones the board for every state private char[][] cloneBoard(char[][] board) { char[][] newBoard = new char[board.length][board[0].length]; copyIntoBoard(board, newBoard); return newBoard; } } public static boolean BFS(char[][] board) { // TODO write BFS search algorithm } public static boolean DFS(char[][] board) { // TODO write DFS search algorithm } /** * parameter: index * return: index * Returns the index of a row based on type(6x6 / 9x9) of the board */ private static int getRowForIndex(int idx) { return idx / type; } /** * parameter: index * return: index * Returns the index of a column based on type(6x6 / 9x9) of the board */ private static int getColumnForIndex(int idx) { return idx % type; } /** * Parameters: source board & destination board * return: null * Copies the source board to destination board in every state */ protected static void copyIntoBoard(char[][] src, char[][] dst) { for (int i = 0; i < src.length; i++) { System.arraycopy(src[i], 0, dst[i], 0, src[i].length); } } /** * Parameters: Board & box index number * returns: true / false * Validates the box, returns true if there is no duplicate number in the box else false */ private static boolean isValidSquare(char[][] board, int s) { boolean[] isPresent = new boolean[board.length+1]; for (int r = (s / 3) * height; r < ((s / 3) + 1) * height; r++) { for (int c = (s % 3) * height; c < ((s % 3) + 1) * height; c++) { char value = board[r][c]; if (value == '.') { continue; } int intVal = Character.getNumericValue(value); if (isPresent[intVal]) { return false; } isPresent[intVal] = true; } } return true; } /** * Parameters: Board & column index number * returns: true / false * Validates the box, returns true if there is no duplicate number in the column else false */ private static boolean isValidColumn(char[][] board, int c) { boolean[] isPresent = new boolean[board.length+1]; for (int i = 0; i < board.length; i++) { char value = board[i][c]; if (value == '.') { continue; } int intVal = Character.getNumericValue(value); if (isPresent[intVal]) { return false; } isPresent[intVal] = true; } return true; } /** * Parameters: Board & row index number * returns: true / false * Validates the box, returns true if there is no duplicate number in the row else false */ private static boolean isValidRow(char[][] board, int r) { boolean[] isPresent = new boolean[board.length+1]; for (int i = 0; i < board.length; i++) { char value = board[r][i]; if (value == '.') { continue; } int intVal = Character.getNumericValue(value); if (isPresent[intVal]) { return false; } isPre.

1. import java.util.LinkedList; import java.util.Queue; import java.util.Stack; class
Sudoku_Solver_question { public static int type = 0; public static int height = 0; // Node exploration
holds the sudoku board in every iteration private static class Exploration { char[][] board; int curCell
= 0; // constructor method public Exploration(char[][] board, int curCell) { this.board =
cloneBoard(board); this.curCell = curCell; } // clones the board for every state private char[][]
cloneBoard(char[][] board) { char[][] newBoard = new char[board.length][board[0].length];
copyIntoBoard(board, newBoard); return newBoard; } } public static boolean BFS(char[][] board) {
// TODO write BFS search algorithm } public static boolean DFS(char[][] board) { // TODO write
DFS search algorithm } /** * parameter: index * return: index * Returns the index of a row based on
type(6x6 / 9x9) of the board */ private static int getRowForIndex(int idx) { return idx / type; } /** *
parameter: index * return: index * Returns the index of a column based on type(6x6 / 9x9) of the
board */ private static int getColumnForIndex(int idx) { return idx % type; } /** * Parameters: source
board & destination board * return: null * Copies the source board to destination board in every
state */ protected static void copyIntoBoard(char[][] src, char[][] dst) { for (int i = 0; i < src.length;
i++) { System.arraycopy(src[i], 0, dst[i], 0, src[i].length); } } /** * Parameters: Board & box index
number * returns: true / false * Validates the box, returns true if there is no duplicate number in the
box else false */ private static boolean isValidSquare(char[][] board, int s) { boolean[] isPresent =
new boolean[board.length+1]; for (int r = (s / 3) * height; r < ((s / 3) + 1) * height; r++) { for (int c =
(s % 3) * height; c < ((s % 3) + 1) * height; c++) { char value = board[r][c]; if (value == '.') {
continue; } int intVal = Character.getNumericValue(value); if (isPresent[intVal]) { return false; }
isPresent[intVal] = true; } } return true; } /** * Parameters: Board & column index number * returns:
true / false * Validates the box, returns true if there is no duplicate number in the column else false
*/ private static boolean isValidColumn(char[][] board, int c) { boolean[] isPresent = new
boolean[board.length+1]; for (int i = 0; i < board.length; i++) { char value = board[i][c]; if (value ==
'.') { continue; } int intVal = Character.getNumericValue(value); if (isPresent[intVal]) { return false; }
isPresent[intVal] = true; } return true; } /** * Parameters: Board & row index number * returns: true /
false * Validates the box, returns true if there is no duplicate number in the row else false */ private
static boolean isValidRow(char[][] board, int r) { boolean[] isPresent = new
boolean[board.length+1]; for (int i = 0; i < board.length; i++) { char value = board[r][i]; if (value ==
'.') { continue; } int intVal = Character.getNumericValue(value); if (isPresent[intVal]) { return false; }
isPresent[intVal] = true; } return true; } /** * parameter: board * return: null * prints the board/matrix
in the console */ public static void print_matrix(char[][] board){ int type = board.length; for(int i = 0;
i<type;i++){ for(int j=0;j<type;j++){ System.out.print(board[i][j]+" "); } System.out.println(" "); } } /** *
Start of the program main function */ public static void main(String args[]){ // 6x6 sudoku board
char[][] board_6x6 = {{'.','.','.','.','4','.'}, {'5','6','.','.','.','.'}, {'3','.','2','6','5','4'}, {'.','4','.','2','.','3'},
{'4','.','.','.','6','5'}, {'1','5','6','.','.','.'}}; // type holds the length of the board type = board_6x6.length; //
height holds the height of each box in the board height = board_6x6.length/3; // prints the problem
board System.out.println("Problem board is: "); print_matrix(board_6x6); // Solve the problem
board using BFS boolean status = BFS(board_6x6); // based on the status print the solution
if(status){ System.out.println("n BFS - Solution board is: "); print_matrix(board_6x6); }else{
System.out.println("n BFS - No Solution found"); } // solve the problem using DFS status =
DFS(board_6x6); // based on the status print the solution if(status){ System.out.println("n DFS -

2. Solution board is: "); print_matrix(board_6x6); }else{ System.out.println("n DFS - No Solution
found"); } char[][] board_9x9 = {{'.','.','.','8','4','.','6','5','.'}, {'.','8','.','.','.','.','.','.','9'},
{'.','.','.','.','.','5','2','.','1'}, {'.','3','4','.','7','.','5','.','6'}, {'.','6','.','2','5','1','.','3','.'}, {'5','.','9','.','6','.','7','2','.'},
{'1','.','8','5','.','.','.','.','.'}, {'6','.','.','.','.','.','.','4','.'}, {'.','5','2','.','8','6','.','.','.'}}; // type holds the length of
the board type = board_9x9.length; // height holds the height of each box in the board height =
board_9x9.length/3; // prints the problem board System.out.println("Problem board is: ");
print_matrix(board_9x9); // Solve the problem board using BFS boolean status1 =
BFS(board_9x9); // based on the status print the solution if(status1){ System.out.println("n BFS -
Solution board is: "); print_matrix(board_9x9); }else{ System.out.println("n BFS - No Solution
found"); } // Solve the problem board using DFS status1 = DFS(board_9x9); // based on the status
print the solution if(status1){ System.out.println("n DFS - Solution board is: ");
print_matrix(board_9x9); }else{ System.out.println("n DFS - No Solution found"); } } }