POJ 1321 棋盘问题

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类似于八皇后问题，DFS入门题

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

int n, k;
char str[10][10];
int a[10][10], cnt, vis[10];


void DFS(int cur,int num)
{
    for (int i = 0; i != n; ++i)
        if (a[cur][i] && !vis[i])
        {
            vis[i] = 1;
            if (num == k-1) cnt++;
            for (int j = cur+1; j < n; ++j)
                DFS(j,num+1);

            vis[i] = 0;
        }
}

int main()
{
    while (cin >> n >> k && n != -1)
    {
        for (int i = 0; i != n; ++i)
            scanf("%s",str[i]);

        for (int i = 0; i != n; ++i)
            for (int j = 0; j != n; ++j)
                if (str[i][j] == '#')
                    a[i][j] = 1;
                else
                    a[i][j] = 0;

        cnt = 0;
        for (int i = 0; i != n; ++i)
        {
            memset(vis,0,sizeof(vis));
            DFS(i,0);
        }
        cout << cnt << endl;

    }
    return 0;
}