Codeforces Round #228 (Div. 2) B. Fox and Cross

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    int n;
    cin >> n;
    vector<string> board(n);
    int cnt = ;
    for(int i =  ; i < n; ++ i ){
        cin >> board[i];
    }

    for(int i =  ; i < n-; i ++ ){
        for(int j =  ; j < n-; j ++ ){
            if(board[i][j] == '#' &&  board[i-][j] == '#' &&
                 board[i+][j]=='#' && board[i][j-]=='#' && board[i][j+]=='#'){
                board[i][j]='.';
                board[i+][j]='.';
                board[i-][j]='.';
                board[i][j-]='.';
                board[i][j+]='.';
            }
        }
    }

    for(int i =  ; i < n; ++i){
        if(board[i].find('#')!=string::npos){
            cout<<"NO"<<endl;
            return ;
        }
    }
    cout<<"YES"<<endl;
    return ;
}