八皇后问题

对列数(1-8)全排列，让每一行中的插入的数在列上没有重复

判断斜线方向是否存在多的皇后

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

int ans[10];
bool b[10];

void out()
{
    int i,j;
    for(i = 1; i <= 7; i++)
        for(j = i+1; j <= 8; j++)
            if(i-j == -abs(ans[i]-ans[j])) return;
    
    for(i = 1; i <= 8; i++)
        cout << "(" << i << "," << ans[i] << ")" << endl;
    cout << endl;
}

void dfs(int num)
{
    if(num >= 9)
    {
        out();
        return ;
    }
    
    int i;
    for(i = 1; i <= 8; i++)
    {
        if(b[i] == false)
        {
            b[i] = true;
            ans[num] = i;
            dfs(num+1);
            /*
            for(int j = 1; j <= 8; j++)
                cout << j << ":" << ans[j] << endl;
            cout << endl;
            */    
            cout << num << "  " << i << endl;
            ans[num] = 0;
            b[i] = false;
        
            
            
        }
    }
}

int main()
{
    dfs(1);
    return 0;
}