void find_next_continuation(const board_t* board, size_t* i_row, size_t* i_col,
digits_t* digits) {
size_t i, j, best_row, best_col;
digits_t tmp_digits, best_digits;
int min_possibilities = NO_MOVE_POSSIBLE;
for (i = 0; i < NROWS; i++) {
for (j = 0; j < NCOLS; j++) {
if (EMPTY == get_digit(board, i, j)) {
count_digits(board, i, j, &tmp_digits);
int n_possible = count_possibilities(&tmp_digits);
assert(n_possible > 0);
assert(n_possible < NDIGITS);
if (n_possible < min_possibilities) {
min_possibilities = n_possible;
best_row = i;
best_col = j;
best_digits = tmp_digits;
}
}
}
}
assert(min_possibilities != NO_MOVE_POSSIBLE);
memcpy(digits, &best_digits, sizeof(digits_t));
*i_row = best_row;
*i_col = best_col;
}
bool is_dead_end(const board_t* board)
{
size_t i, j;
bool dead_end = false;
for (i = 0; (i < NROWS) && (!dead_end); i++) {
for (j = 0; (j < NCOLS) && (!dead_end); j++) {
field_t value = get_digit(board, i, j);
debugf("[%u,%u] == %d\n", i, j, value);
if (EMPTY == value) {
digits_t digits;
count_digits(board, i, j, &digits);
int n_possibilities = count_possibilities(&digits);
if (0 == n_possibilities) {
dead_end = true;
debugf("[%lu,%lu] = %d, dead end\n", i, j, value);
}
}
}
}
return dead_end;
}
static int try_possibility(char pattern[9][9], char possibilities[9][9][9]) {
int iterations = 0;
bool solved = false;
int lowestx = 0;
int lowesty = 0;
int lowest = 9;
for (int x = 0; x < 9; x++) {
for (int y = 0; y < 9; y++) {
if (pattern[x][y] == ' ') {
if (lowest > count_possibilities(possibilities, x, y)) {
lowest = count_possibilities(possibilities, x, y);
lowestx = x;
lowesty = y;
}
}
}
}
if (lowest != 9) {
while ((lowest > 0) && (!solved)) {
iterations++;
char testpattern[9][9];
char testpossibilities[9][9][9];
bool loadprob = false;
for (int x = 0; x < 9; x++) {
for (int y = 0; y < 9; y++) {
testpattern[x][y] = pattern[x][y];
for (int z = 0; z < 9; z++) {
testpossibilities[x][y][z] = possibilities[x][y][z];
if ((x == lowestx) && (lowesty == y) && (possibilities[x][y][z] != ' ') && (!loadprob)) {
testpattern[x][y] = possibilities[x][y][z];
possibilities[x][y][z] = ' ';
testpossibilities[x][y][z] = ' ';
loadprob = true;
}
}
}
}
printf("\n===\n");
print_pattern(testpattern);
printf("\n===\n");
switch(check_solved_legal(testpattern)) {
case 1 :
solved = true;
print_pattern(testpattern);
printf("\nSolved!\n");
printf("\nIterations: %d\n", iterations);
end = clock();
time_spent = (double)(end - begin) / CLOCKS_PER_SEC;
printf("\nTime to run: %f\n", time_spent);
exit(EXIT_SUCCESS);
return iterations;
case -1 :
printf("\nillegal moves\n");
break;
case 0 :
iterations += try_possibility(testpattern, testpossibilities);
}
lowest--;
}
}
return iterations;
}
