bool is_checked(const int counter, int board[]) {
int row_1, row_2;
for (int col_1=0; col_1<counter; col_1++){
row_1 = board[col_1];
for (int col_2=col_1+1; col_2<counter; col_2++) {
row_2 = board[col_2];
if (threatens(row_1, row_2, col_1, col_2)) return false;
}
}
return true;
}
// the i-th queen is in the i-th row
// we only check rows up to end_idx
// so that the same function can be used for backtracking and checking the final solution
static bool good(const std::vector<int> &pos, int end_idx)
{
for (int row_a = 0; row_a < end_idx; row_a++) {
for (int row_b = row_a + 1; row_b < end_idx; row_b++) {
int col_a = pos[row_a];
int col_b = pos[row_b];
if (threatens(row_a, col_a, row_b, col_b)) {
return false;
}
}
}
return true;
}
