学步园

原题：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=1002

#include<stdio.h>
#include<string.h>

char maps[5][5];
int n,ans;
int judge(int x,int y)
{
	int temp;

	if(maps[x][y] == 'X' || maps[x][y] == 'C')return 0;

	for(temp=y-1;temp>=1;temp--)
	{
		if(maps[x][temp] == 'X')break;
		else if(maps[x][temp] == 'C')return 0;
	}

	for(temp=y+1;temp<=n;temp++)
	{
		if(maps[x][temp] == 'X')break;
		else if(maps[x][temp] == 'C')return 0;
	}

	for(temp=x-1;temp>=1;temp--)
	{
		if(maps[temp][y] == 'X')break;
		else if(maps[temp][y] == 'C')return 0;
	}

	for(temp=x+1;temp<=n;temp++)
	{
		if(maps[temp][y] == 'X')break;
		else if(maps[temp][y] == 'C')return 0;
	}

	return 1;
}

void dfs(int k)
{
	int i,j;
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=n;j++)
		{
			if(judge(i,j))
			{
				maps[i][j] = 'C';
				dfs(k+1);
				maps[i][j] = '.';
			}
		}
	}

	ans = ans>k?ans:k;
}
int main()
{
	int i,j;
	while(1)
	{
		scanf("%d",&n);
		if(n == 0)break;
		scanf("\n");
		for(i=1;i<=n;i++)
		{
			for(j=1;j<=n;j++)
				scanf("%c",&maps[i][j]);
			if(i<n)
			scanf("\n");
		}

		ans = 0;
		dfs(0);
		printf("%d\n",ans);
	}
	return 0;
}