Eight Queens Puzzle

eight_queen.cpp

#include <iostream>

using namespace std;

int board[8][8];

int check(int x, int y) {
    int p, q;

    for (p = 0; p < x; p++)
        if (board[p][y] == 1)
            return 0;

    p = x; q = y;

    while (p > 0 && q > 0)
        if (board[--p][--q] == 1)
            return 0;
    
    p = x; q = y;

    while (p > 0 && q < 7)
        if (board[--p][++q] == 1)
            return 0;

    return 1;    
}

void show_board(void) {
    int x, y;

    for (y = 0; y < 8; y++) {
        for (x = 0; x < 8; x++)
            cout << (board[x][y]? 'Q' : 'x');
        cout << endl;
    }
}

int solve(int x) {
    int i;

    if (x ==8)
        return 1;

    for (i = 0; i < 8; i++) {
        if (check(x, i)) {
            board[x][i] = 1;
            if (solve(x + 1))
                return 1;
            else
                board[x][i] = 0;
        }
    }
    return 0;
}

int main(void) {
    if (solve(0))
        show_board();
    return 0;
}