Eight Queen Problem

solution:

const int N = 8;
int position[N];
 
// Check if a position is safe
bool isSafe(int queen_number, int row_position)
{
        // Check each queen before this one
        for(int i=0; i<queen_number; i++)
        {
                // Get another queen's row_position
                int other_row_pos = position[i];
 
                // Now check if they're in the same row or diagonals
                if(other_row_pos == row_position || // Same row
                        other_row_pos == row_position - (queen_number-i) || // Same diagonal
                        other_row_pos == row_position + (queen_number-i))   // Same diagonal
                        return false;
        }
        return true;
}
 
 
// Recursively generate a tuple like [0 0 0 0], then [0 0 0 1] then etc...
void solve(int k)
{
        if(k == N) // We placed N-1 queens (0 included), problem solved!
        {
                // Solution found!
                cout << "Solution: ";
                for(int i=0; i<N; i++)
                        cout << position[i] << " ";
                cout << endl;
        }
        else
        {
                for(int i=0; i<N; i++) // Generate ALL combinations
                {
                        // Before putting a queen (the k-th queen) into a row, test it for safeness
                        if(isSafe(k,i))
                        {
                                position[k] = i;
                                // Place another queen
                                solve(k+1);
                        }
                }
        }
}
 
int main()
{
        solve(0);
 
        return 0;
}