sudoku

[hashimtk]

Hi,
i done a sudoku solving program ,and i got solution for easy sudoku, Can u explain any logic to find out medium and hard sudoku.

[r035198x]

Hi,
i done a sudoku solving program ,and i got solution for easy sudoku, Can u explain any logic to find out medium and hard sudoku.

I hope you went through this article.

[JosAH]

I wrote that article and solver and I'm curious how it behaves on 'difficult' problems.
Please let us know the results you find.

kind regards,

Jos

[hashimtk]

I wrote that article and solver and I'm curious how it behaves on 'difficult' problems.
Please let us know the results you find.

kind regards,

Jos

[CODE=java] package hitori;

public class Sudoku {


public final static int puzzle[][] = {
{2, 0, 0, 7, 4, 0, 8, 0, 1},
{8, 0, 0, 2, 9, 0, 5, 0, 6},
{0, 7, 5, 0, 8, 0, 0, 0, 0},
{0, 0, 0, 8, 2, 0, 6, 0, 0},
{4, 0, 2, 0, 0, 0, 9, 0, 8},
{0, 0, 3, 0, 6, 9, 0, 0, 0},
{0, 0, 0, 0, 1, 0, 4, 6, 0},
{3, 0, 1, 0, 7, 8, 0, 0, 9},
{6, 0, 9, 0, 5, 4, 0, 0, 7}
};


static boolean possibilities[][][] = new boolean[9][9][9];


public static void fillPossibiliti esMatrix() {
for (int row =0; row <puzzle.lengt h; row++) {
for (int column =0; column <puzzle.lengt h; column++) {
for (int number = 0; number<puzzle.l ength; number++){
possibilities[row][column][number] = true;
}
}
}
}

public static void resetPossibilit iesValue(int row, int column, int number) {

resetRow( row, number);
resetColumn( column, number);
int rebox=getBox(ro w,column);
resetBox( rebox, number);


}

/**
* Looks into the possibilities matrix and if the cell can have only one
* possible value, then returns the correct number from 1 to 9,
* else returns -1
*/
public static void getCellSolution (int row, int column) {
int trues = 0,value = 0;
for (int number = 0;number<9;numb er++) {
if (possibilities[row][column][number]) {
trues++;
value = number +1;
}
}
if (trues == 1) {
puzzle[row][column] = value;
}
}
/**
* Prints the Sudoku as 9 rows of 9 columns each
*/
public static void printSudoku() {
for( int row=0; row<puzzle.leng th; row++) {
for( int column=0; column<puzzle.l ength; column++) {
System.out.prin t(puzzle[row][column] + " ");
}
System.out.prin tln(" ");
}
}

public static void resetRow(int rerow, int number) {
for( int column=0; column<puzzle.l ength; column++) {
possibilities[rerow][column][number-1] = false;
}
}

public static void resetColumn(int recolumn, int number) {
for(int row=0; row<puzzle.leng th; row++) {
possibilities[row][recolumn][number-1] = false;
}
}

public static void resetBox(int box, int number) {
switch(box) {
case 1: for ( int row = 0; row<3; row++) {
for (int column= 0; column<3; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 2: for ( int row = 0; row<3; row++) {
for (int column= 3; column<6; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 3: for ( int row = 0; row<3; row++) {
for (int column= 6; column<9; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 4: for ( int row = 3; row<6; row++) {
for (int column= 0; column<3; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 5: for (int row = 3; row<6; row++) {
for (int column= 3; column<6; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 6: for ( int row = 3; row<6; row++) {
for (int column= 6; column<9; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 7: for ( int row = 6; row<9; row++) {
for (int column= 0; column<3; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 8: for ( int row = 6; row<9; row++) {
for (int column= 3; column<6; column++) {
possibilities[row][column][number-1] = false;
}
} break;
case 9: for ( int row = 6; row<9; row++) {
for (int column= 6; column<9; column++) {
possibilities[row][column][number-1] = false;
}
} break;
}
}

public static int checkSudoku() {
int count = 0;
for(int row = 0; row< 9; row++) {
for ( int column = 0; column<9; column++) {
if (puzzle[row][column] != 0) {
count++;
}
}
}
return count;
}
static int getBox(int row, int column) {
int box = 0;
box= ( 3*row/3)+(column/3) +1;
return box;
}


public static void main(String argv[]) {
int row,column,numb er;
fillPossibiliti esMatrix();
while (checkSudoku() < 81) {
for ( row=0; row<puzzle.leng th; row++) {
for ( column=0; column<puzzle.l ength;column++) {
number = puzzle[row][column];
if(number != 0) {
resetPossibilit iesValue (row,column,num ber);
}
else {
getCellSolution ( row, column);
}
}
}
}
printSudoku();
}
}[/CODE]

[JosAH]

Hi, did your program solve that puzzle? The solver described in that article solved
it instantaneously (I didn't time it though).

kind regards,

Jos