int sudokuHelper(int puzzle[][9], int row, int column)
{
if (9 == row) { return 1; }
if (puzzle[row][column])
{
if (column == 8)
{
if (sudokuHelper(puzzle, row+1, 0)) return 1;
}
else
{
if (sudokuHelper(puzzle, row, column+1)) return 1;
}
return 0;
}
for (int nextNumber=1; nextNumber<10; nextNumber++)
{
if(isOk(nextNumber, row, column))
{
puzzle[row][column] = nextNumber;
if (column == 8)
{
if (sudokuHelper(puzzle, row+1, 0)) return 1;
}
else
{
if (sudokuHelper(puzzle, row, column+1)) return 1;
}
puzzle[row][column] = 0;
}
}
return 0;
}
int main(int argc, char *argv[]){
// Read the file puzzle.txt to get the puzzle
// Store it in an 2D Array
read_puzzle();
// Solve the puzzle
int solved = sudokuHelper(puzzle, 0, 0);
// Save the solution to solution.txt
if (solved == 1){
printf("Puzzle solved!\n");
save_solution();
} else {
printf("Could not find a solution to this puzzle.");
}
return EXIT_SUCCESS;
}
int sudokuHelper(int puzzle[9][9], int row, int column) {
print_puzzle();
printf("Started recursive call. Row: %d\tColumn: %d\n", row, column);
position current;
current.row = row;
current.column = column;
int val = 1;
// If all rows have been filled, then return 1
if (9 == row) {
return 1;
}
// check if cell is empty
if (puzzle[row][column] != 0) {
printf("Cell is not Empty!\n");
// If its the last column go to next row
if (column == 8) {
// Call method on next row, first column
if (sudokuHelper(puzzle, row+1, 0)) return 1;
} else {
// Call method on next column
if (sudokuHelper(puzzle, row, column+1)) return 1;
}
return 0;
}
// Cell is empty
// Try all the values until you find one that is valid
for (; val < 10; val++) {
printf("Checking for value: %d\n", val);
current.value = val;
// Create threads to do the checking at same time
pthread_t row_t;
pthread_t column_t;
pthread_t box_t;
pthread_create(&row_t, 0, valid_in_row, (void *) ¤t);
pthread_create(&column_t, 0, valid_in_column, (void *) ¤t);
pthread_create(&box_t, 0, valid_in_box, (void *) ¤t);
// Wait for threads to finish checking
pthread_join(row_t, 0);
pthread_join(column_t, 0);
pthread_join(box_t, 0);
// if the value is valid in current cell
if (valid_box && valid_row && valid_column) {
printf("%d was a valid value.\n", val);
// Save the value to the current cell
puzzle[row][column] = val;
// Move on to next cell
// If 0 is returned, means that a valid value could not be found for the next cell
// and this cell has to be changed
if (column == 8) {
if (sudokuHelper(puzzle, row+1, 0) == 1) return 1;
} else {
if (sudokuHelper(puzzle, row, column+1) == 1) return 1;
}
// The value we chose was incorrect so reset the cell to 0
// and continue the loop
puzzle[row][column] = 0;
}
}
// If none of the values were valid, then one of the previous cells is wrong
// so we go up a level and continue there
return 0;
}
int solveSudoku(int puzzle[][9])
{
//init();
return sudokuHelper(puzzle, 0, 0);
}
