这题题目大致意思就是找它所有的.能否满足五字格，简单遍历就好，直接上代码

#include
     
      #include
      
       #include
       
        #include
        
         using namespace std;const int maxn = 100;char a[maxn][maxn];int lazy[maxn][maxn];int main(){    int x;    cin >> x;        memset(lazy, 0, sizeof(lazy));    int ans = 0;    for (int i = 0; i < x; i++)    {        getchar();        for (int  j = 0; j < x; j++)        {            scanf("%c", &a[i][j]);            if (a[i][j] == '.')            {                ans++;                lazy[i][j] = 1;            }        }    }    int sum = 0;    for (int i = 0; i < x; i++)    {        for (int j = 0; j < x; j++)        {            if (lazy[i][j] == 0||lazy[i][j]==2)continue;            if (lazy[i][j] == 1)            {                if (lazy[i - 1][j] == 1 && lazy[i + 1][j] == 1 && lazy[i][j - 1] == 1 && lazy[i][j + 1] == 1)                {                    sum += 5;                    lazy[i][j] = 2;                    lazy[i - 1][j] = 2;                    lazy[i + 1][j] = 2;                    lazy[i][j + 1] = 2;                    lazy[i][j - 1] = 2;                }            }        }    }    if (sum == ans)    {        printf("YES\n");    }    else    {        printf("NO\n");    }}