八皇后

#include <iostream>
#include <cmath>
using namespace std;

#define N 8

bool ground[N + 1][N + 1] = {0};

bool is_legal(bool ground[N + 1][N + 1], const int &i, const int &j)
{

    for (int m = 1; m <= i - 1; ++m) {
        for (int n = 1; n <= N; ++n) {  
            if (ground[m][n]) {
                if ( n == j || abs(i - m) == abs(j - n) )
                    return false;
            }
        }
    }
    return true;
}

void output(bool ground[N + 1][N + 1])
{
    static int count = 1;
    cout << "possible result " << count++ << endl;
    for (int i = 1; i <= N; i++) {
        for (int j = 1; j <= N; j++) {
            ground[i][j] ? (cout << "Q ") : (cout << ". ");
        }
        cout << endl;
    }
    cout << endl;
}

void eight_queen(const int i)
{
    if (i > N)  
        output(ground);
    else
        for (int j = 1; j <= N; ++j) {
            ground[i][j] = 1;
            if ( is_legal(ground, i, j) )
                eight_queen(i + 1);
            ground[i][j] = 0;
        }
}

int main(void)
{
    eight_queen(1);

    return 0;
}