题解

不给公式其实也能写出来

#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin >> n;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(i+j==n/2+2)cout << "#";
            else if(abs(j-i)==n/2)cout << "#";
            else if(i+j==n+n/2+1)cout << "#";
            else cout << ".";
        }
        cout << endl;
    }
    return 0;
}